What’s the difference between streaming and downloading a video, and how does it impact the limits my ISP imposes?

Watching online video is popular but if your ISP imposes a data transfer limit there are some important differences between streaming and downloading.

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If I put a YouTube video in my Favorites folder on the site, does each viewing of the video from the Favorites site count towards my download usage allowance with my ISP? Presumably the video is streamed each time I view it, but does this actually count as downloading? If it does, what is the difference between streaming and downloading in this case?

I’m honestly not sure exactly which “My Favorites” you’re referring to, since there could be several. I’ll assume you mean the feature of the YouTube website itself.

YouTube actually works using “download”, not “streaming” – which is of course confusing. It gets worse, since whether or not it gets downloaded each time you view it depends on how long ago you last viewed it, and how busy you’ve been since.

Let’s start with the terminology: what’s it mean to “stream” versus “download”?

Download you’re probably already familiar with: it’s simply a file copy – nothing more, nothing less. When you download a file you’re just making a copy of that file which is stored on a server somewhere on your local machine.

A stream is a different concept; there is no file. A stream is simply a that: a stream of data, 1’s and 0’s, that are being sent from some server to your machine.

YouTube actually uses a download model to provide you with videos.

A bottle of water might be comparable to a download – you can move it around, you can put it in different places, use it when you like. A hose with water pouring out of it is more comparable to a stream – you have to use the water as it comes out of the hose, or it’s gone.

The Download Approach: YouTube

YouTube actually uses a download model to provide you with videos.

When you first begin to watch a video, the player begins to download it – it quite literally copies the file from the YouTube servers to your internet browser cache. The “trick”, if you want to call it that, is that it begins playing the file before the download is done. That can make it seem like it’s streaming, but it’s not.

You can even see this in action by watching the YouTube progress bar:
YouTube Player Progress while downloading

You can see that the video has begun to play, even though it’s not fully downloaded. If the player ever catches up to the
download progress point, then the playback will pause or stutter – the download’s not fast enough to keep up.

If you pause, or if you have a connection that’s fast enough, eventually you’ll reach this state:
YouTube Player Progress after fully downloaded
At this point, the file has been fully downloaded.

If you replay the file without leaving the page, the file does not need to be downloaded again. Each replay simply reads the file from the browser cache again to display the video.

If you do something else – say you watch a few other videos – and then come back to this video it may still be in the cache, and thus may not need to be downloaded again.

On the other hand, you might have viewed enough other content that the browser needed to delete older content – such as your video – to make room. As a result, your video might not be in the cache, and thus might need to be downloaded again.

Ultimately, whether or not a video you’ve previously viewed needs to be downloaded depends on these three things:

  • the size of your browser cache
  • the amount of browsing you’ve done since the last time you viewed the video
  • whether or not the video was updated on the server (this can also force a download)

Of course you can tell what’s happening by watching the YouTube progress bar.

The Streaming Approach: Hulu

All that is complex in comparison to the very simple concept of a streaming video, which gives you no choice. Each time you watch such a video it’s streamed directly from the server to the video player without being cached at all. There is no separate “download progress” indicator, since there’s no separate download. If you restart the video, it restarts the stream back at the beginning.

I believe videos at Hulu.com are streams.

Because internet connections can be inconsistent, streaming video players often include some kind of buffering, where they actually do receive a certain amount of the stream before they actually begin playing it, or in response to pausing the video they continue to receive it to fill that buffer:
Hulu, a streaming player, paused and buffering
Change your position in a streaming video, and the buffer is invalidated; the stream must restart at the new position you’ve selected.

Managing your bandwidth and data transfer limits.

Everything you watch, every time you watch it, using a streaming video, counts towards any data transfer limits imposed by your ISP. Watch a 100 megabyte movie 10 times, and you’ve just eaten up a gigabyte of your allotment.

What counts against your allotment when watching a download-style video depends on whether or not it’s already been downloaded and in your browser’s cache. If it’s already there, subsequent viewings don’t count. If it needs to be re-downloaded, then that data transfer does count.

There are tools that in some cases can help, but they may skirt or even cross the line on some legal issues.

For example, there is software that will allow you to capture streaming video into a file that you can then keep and replay from your hard drive as often as you like without needing to re-download. How successful this is really depends on many factors including the speed and capabilities of your PC and the speed of your internet connection. Screen recording tools like Camtasia may work, and there are dedicated utilities such as the various tools from Replay and others.

For YouTube specifically there are many results returned when you search for “download YouTube” that will place the downloaded file not in the browser’s cache somewhere, but in a location that you can specify and then keep. Unfortunately, this type of download is not officially sanctioned by YouTube, and thus these tools often break as YouTube makes changes to their technologies.

The bottom line is that video can be large, and regardless of whether or not you actually have the ability to control it, it’s important to understand exactly what’s being downloaded or streamed, particularly if your ISP is imposing data transfer limits.

There are 18 comments:

  1. Ian Ross Reply

    I am on mobile broadband dongle at home (uk). For a certain amount of money, I can have various amounts of data usage. I have noticed as you are downloading/streaming, you are not only taking data down, you are also putting data up. If you are on a limited budget with your ISP, then I would suggest trying to get a program which wil let you see how much data thruput you have. For every 20mb coming down, about 2-3mb is going back up.
    The program I am thinking about is Networx. I hope Leo lets this thru as it’s not advertising in this sense. A very useful little free program for those with limited budget and, limited internet connection data rate.

  2. wilma Reply

    Is there a way to tell how many mg it takes to see a youtube video lasting maybe 5 minutes?

  3. john devaney Reply

    that was simlpy brilliant leo. you explained that very well. i’m not a techie/geek but i do believe i learnt something today, and understood it!….. very informative.thank you
    regards
    john devaney

  4. Azrael Reply

    Wilma, the size of a 5 min video can vary between 500kB (usually on YouTube the lowest quality ones are around 3MB) and 1GB for an uncompressed DV (usually on YouTube the HQ quality ones are around 25MB). There isn’t anything you can do to find the real size of the video apart viewing it – better the image and sound, bigger the file.

  5. Bill Reply

    I think that the asker was really trying to say.
    I can download a file and view it or make a link to the file and view it, what is the difference for my limits.

    Really good detective work on the YouTube information.

    For the asker: There is software out there that will capture the files for videos. If you do that, you can download the video one time and then view the file that is on your hard drive instead of downloading it (anything you view on the internet is downloading information from the server to your computer) again when you want to see it again.

  6. Unmesh Dave Reply

    Well,
    I do not agree with Leo. Youtube does provide option to remember the downloaded video. See (+) sign on video click on it and you can view it even when you are offline.

    Unfortunately that option is rarely available in that way – certainly not on all videos, and perhaps not for all users. In my tests it just re-downloads the video if it’s not in your cache.

    Leo
    02-Sep-2009

  7. Dan Shanis Reply

    Hi, You might mention that to change cache size in Firefox, you can go to Tools then Options, and then go to the Advanced tab, Select Network. You can increase cache size there.

  8. Gwyn Reply

    Many thanks for another clear and comprehensive answer to my question. ( A latte is on its way .)

  9. John N. Reply

    May I suggest a program such as Video Cache Viewer. Such utilities simply weed out the videos (in any format) you have viewed since you last cleared your browser. There will be many, but you can just ignore/delete any shockwave .swf files right off the bat, they are always ads. Then just look through what’s left, and you should find the one/s you want. Select them, and save or copy to a pre-designated folder. U-Tube vids are .flv, usually quite tidy in size.
    There you go!

  10. Merna B. Reply

    Here in Australia our ABC (Australian Broadcasting Corporation) promotes its iView link at which viewers can catch up with programmes we might have missed. The programmes are streamed, most are available for fourteen days, and iView is unmetered with five ISPs. (“The ABC is in negotiation with other ISPs to offer ABC iView unmetered to their customers.”) I am fortunate to be with one of the five.

    When one starts iView, the site contains a box indicating whether usage will be metered or unmetered, a graph from “Poor quality” to “High quality,” and the following text: “Your internet connection can stream video at ____ . We recommend 1.1 Mbps (1126 kbps) or above for optimum viewing.”

    In my case the graph shows me just about in the middle between “Poor quality” and “High quality” — I am just below the middle line. The text currently reads “… can stream video at 421 kbps”. On the occasions I have used iView there has not been much of a variation from that figure. That quality and speed mean that when I try to use iView, the programme stutters. It runs for a minute or two and then pauses as the streaming “catches up” with what I am viewing. The first couple of times I tried to watch something, I gave up very quickly. However, eventually the day came when I REALLY wanted to see a programme and didn’t want to give up. I also REALLY didn’t want to put up with the stuttering / buffering.

    I had found in the past that I could solve the problem with YouTube videos by noting their length when starting them, then muting my PC’s sound and going to another browser window (or playing Hearts or doing emails) until just about the time the video was due to end. I would then go back to it, turn my sound back on, and use the “Replay” option to watch the YouTube video without experiencing the stuttering. This method, however, did not work with iView’s streaming video (as I found to my dismay when I tried it and after the half hour or more of the programme’s time had expired — in comparison to usually much shorter waiting times for YouTube videos — I could only start it again complete with stuttering).

    Since then I have experimented and found a solution. I start iView and then go to the programme I want to watch and start it. As soon as it has started to play, I click on the Play/Pause button. Then I do something else for ten to fifteen minutes (emails, surf in another window, put a load of washing in the machine, rake a few leaves, etc.). When I come back and click on the Play/Pause button again, the programme plays without stutter for some time. Eventually it begins to stutter again, and I use the Play/Pause button again.

    Of course, if I were watching the programme on the ABC on TV, there wouldn’t be these interruptions. To “console” myself about them, I think of them as “commercial breaks” (albeit extended ones) when I would most likely get up and do something else anyway. (For readers not familiar with Australia’s ABC, it has no commercials. The only things it screens other than programmes are promos and previews for its own content.)

    I discovered the BBC has a similar programme when I was trying to find a BBC production that was no longer on iView. I also learned that content agreements and/or management rights dictate the length of time the programmes remain available for online viewing at both sites. I have not provided a link for iView because it is for domestic consumption only (as is the BBC link).

    As I cannot utilise the BBC link, I have not checked whether the BBC has any “free content” arrangement with any ISPs. Neither have I checked whether any American networks have comparable arrangements, for domestic or other viewers. Perhaps American viewers could enlighten me / us about whether any exist.

    Merna B.

  11. Chris Reply

    There’s an extension for firefox called DownloadHelper. It sits next to your address bar idle until there is some kind of embedded media being played in one of your tabs, where it then becomes active. Clicking the icon will show you a list of the embedded media with extension and everything. If you click on one, it begins the regular download.

    I use it all the time and it works for youtube and any other site with embedded audio or video!

  12. Kenneth Crook Reply

    I have found two options to save a video download to my computer.
    One is keepvid.com. You copy the URL of the Youtube page you are watching, go to http://www.keepvid.com and paste the link. Then copy the file to where you want to keep it.
    Second is the browser tool, FlashCatch from http://www.ieaddons.com. It puts an icon on the toolbar, when viewing a video click on the icon to save the file.

  13. samth Reply

    Thanks, now there is a popular software “StreamTrnsport”,It can download video from YouTube, Hulu and other website. it is a freeware.

  14. Ellie Reply

    We have a mi-fi from verizon for our internet connection. I believe their is a limit or cap on our usage. How do we determine how much data it takes to stream a 2 hour TV episode four times a month.

    I believe that Verizon has a data-usage app or can tell you how much you’ve used on their web site. I would note the amounts before and after streaming a movie and use that as a guide. (I’d also give the Verizon data a day to catch up, as I doubt that it is real time.) While there are some cumbersome ways to measure your own usage what really matters is what Verizon things you’ve used.

    Leo
    17-Jan-2011

  15. drew whitey Reply

    Your article doesn’t appear to be correct to me. Cross-checking with other forums Youtube does not “download” but streams. The feint status indicator is not a download indicator but a stream indicator. The darker indicator is merely the playhead indicator. Besides, when I click on a download button on a website, my downloads folder immediately opens up (using a mac) and I can see the file transferring to my computer in a non-watchable indicator bar. Only by double-clicking on the resulting file, does the file open up (in the appropriate app for viewing). I find it a bit annoying that your answer is possibly incorrect.

  16. Diptarag Reply

    Which will be more efficient way of using data transfer limit– watching a video online or downloading it? I have a high speed internet access so in both case I can watch it without interruption.

  17. Mark J Reply

    @Diptarag
    It’s six of one half a dozen of the other as streaming is downloading without saving. Although if you download it, you’ll have it to watch again if you want.

  18. R Wheeler Reply

    @drew whitey- Your computer does not give download notifications for storing cookies in the cache, but it’s still an automatic download. Leo stated that Youtube downloads the video data into your browsers cache. You are not going to receive a download notification for this, as anything put in the cache is only temporary. When your computers internal memory becomes full, it dumps the cache and starts anew. You can also manually dump your browsers cache to give a small boost to your internet browsing (pages will load faster, games will run smoother, etc.).

    What Leo says makes sense, after viewing something on Youtube, I can immediately watch it over and over again without ever having to rebuffer it. However, after watching a video on a streaming site such as DivXden, at the end if I want to restart the video, I have to rebuffer the whole video again because it wasn’t ever fully downloaded.

    Just remember, just because you didn’t receive a download notification doesn’t mean websites aren’t downloading files to your cache. That’s where most spyware and malware dwells, because it’s so easy to get past your computers security. Most websites will instantly download malware that’s soul purpose is to track where you’ve been and where you go next into your browsers cache for demographic purposes. They’re usually harmless, but a good anti-virus program will prevent the harmful ones from getting in.

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