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For quite some time, about 20% of all flash videos I watch (e.g. YouTube or Vimeo) have been very broken. They become very blocky, as if the stream is corrupted. Here's a still:


(original video)

I've also uploaded a screen capture to show what it looks like over time:

Obviously this makes the video pretty much completely unwatchable.

What didn't help:

  • Reinstalling Flash
  • Reinstalling Firefox
  • Upgrading to the very latest graphics drivers

My system:

  • Win7 x64
  • Firefox 3.6
  • Adobe Flash plugin
  • Intel Core 2 Quad Q6600
  • 8GB RAM
  • ATI HD5770

Any tips on how to fix this?

share|improve this question
What version of Flash Player? – Chealion Aug 18 '10 at 15:07
@Chealion Firefox's "Plugins" tab mentions "", and then one line below it "10.1.r82". – romkyns Aug 18 '10 at 15:40
Can you test your internet connection using and – Tom Wijsman Sep 5 '10 at 20:08
9.85 Mbps / 0.33 Mbps; packet loss 0%; ping 250ms; jitter 70ms (being unusually bad this morning) The video still plays just fine on my Win32 laptop on this same connection. – romkyns Sep 6 '10 at 16:29
up vote 1 down vote accepted

I have been facing similar problems, some of videos were absolutely unwatchable. For me the solution was to disable hardware acceleration (right click on the video, Settings/uncheck Enable hardware acceleration (or something similar - not sure about exact phrases in English as my language is different)). The problem is gone for me.

share|improve this answer

With problems like these, the best bet is usually to try and narrow down the problem.

As you have exhausted the obvious software fixes (upgrading Flash, Firefox & gfx drivers), I'd try to rule out a hardware problem.

Try booting some kind of live CD on the computer (e.g. Ubuntu Live CD or BartPE), install Firefox on it (Ubuntu already has it), install Flash, try the video. Note that there are some issues with the ATI HD5770 under Linux (see ), so make sure you don't run into these.

You might also try:

  • installing a different browser (IE, Chrome, Opera) + Flash to see if it makes a difference
  • run your card with generic VESA drivers (I know, horrible...) to test video
  • download a problematic Youtube video (using one of the many download tools), then play it in a media player (MPlayer, VNC, Windows Media...)

Depending on where you can reprocuce the problems, you'll have to dig further...

Good luck!

Edit: I also remember Adobe Flash having issues with 64-bit systems. Maybe it's a 64-bit specific Flash bug?

share|improve this answer
Some good ideas you're offering them, will run through them. My browser is 32-bit, so it's running a 32-bit version of Flash. – romkyns Sep 6 '10 at 16:28

Video freezes in Firefox could be caused by the Session Restore feature.

By default, Firefox saves your session info on disk every 10 seconds. This protects you from Firefox crashes, so that you can continue browsing from where you were if Firefox restarts. However, it does use the disk and the CPU furiously every 10 seconds.

To increase this interval:

  1. Open Firefox and in the Location/Address Bar type in about:config and hit Enter.
  2. In the “Filter” line at the top of the list type in session to reduce the listings.
  3. Now find “browser.sessionstore.interval” and double click it.
    That number is how many milliseconds between the times that Firefox saves your current browsing session in case of a crash.
  4. Change that number to something different. 300000 is 5 minutes and 120000 is 2 minutes.

Some more advice is contained in the Mozilla Support thread of
Flash video (including YouTube) freezes in firefox

One advice says:

I use this page: press "free java download" the page detect your version, and if you have it lastets version, does not pass anything, but videos reload ( in detecting step)and they can be seen without problem, without having to reload firefox.

Another is:

First try installing the latest version of Flash (you're behind one; there was a recent release) using this procedure to see if that helps:

  1. Download this uninstaller from
  2. Download this installer from
  3. Close Firefox
  4. Run the uninstaller, then the installer
  5. Open Firefox

If that doesn't do it, try it this way:

  1. Download this uninstaller from
  2. Download this installer from
  3. Close Firefox
  4. Run the uninstaller, then the installer
  5. Open Firefox

There's also a rumor going around that Java can cause this. If you'd do this before trying the above stuff and report back, I'd appreciate it:

  1. In Firefox, go to Tools > Options...
  2. Click to the Content tab
  3. Uncheck "Enable Java"
  4. Close the Options window, restart Firefox, try a video
share|improve this answer
It's not freezing like that. I know those freezes very well, and they don't add anything other than an annoying delay; never blockiness. I've got a Core2 Quad Q6600 with 8GB of RAM and an ATI HD5770. – romkyns Sep 6 '10 at 8:12
@romkyns: That's quite respectable hardware you have. It's maybe a problem with the codec you are using. Try to install K-Lite Codecs, although I'm not sure this will help Flash. Also try another player integrated into the browser, like maybe VLC that has its own codecs (again I'm unsure regarding Flash). – harrymc Sep 6 '10 at 8:35
See Flash 64-bit support : Are you using a 32-bits browser? – harrymc Sep 6 '10 at 9:43
@harrymc yes, the browser is 32-bits. I've already got K-Lite Codec Pack (my favourite pack), but I'm pretty certain Flash doesn't use them. – romkyns Sep 6 '10 at 16:26
What happens when you Play YouTube Videos Directly in VLC Media Player as in… – harrymc Sep 6 '10 at 18:23

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