I have the same problem. I noticed it the first time I tried to play a youtube video after upgrading Firefox to 3.6.14. Audio works, but video area is just a white space. Sometimes I notice a very brief flash of video content in the video area when it begins to play, then it goes white again. If I position the cursor where I guess the stop/start button to be (also not visible) and click there I can stop the audio and apparently also the invisible video.

I tried downgrading to Firefox 3.6.13, but that didn't help. Youtube videos play OK in IE8. I have Windows XP SP3.

Note: I did find a fix that works for me. See my reply below.

It appears to be a Flash problem which is also affecting Chrome.

You can still see, when you hover your cursor over the place where the button to play the video in the "Pop-out" box should be at the lower edge of the video screen, the exact location of that button. Left-click on that location and the video will come up in the "Pop-out" box.

Obviously a work-around and not a cure, but better than nothing.

Same problem here.

Hulu and such work fine. Not youtube. I get that same brief "flash" of an image but it goes away.

There are inviable workarounds out there but nothing which really works, as turning off hardware acceleration is not acceptable and the "pop-out" link can't be seen.

I guess the best workaround is to go back to IE7 or IE8 until Mozilla figures out what to do about this.

I too have this problem.

I have Firefox 3.6.14 and Chrome 9.0.597.107.

I updated Flash to the latest build (10.2.152.32), but that didn't help.

I have Windows 7 btw.

The problem started after the last Firefox automatic update.

Prior to that I had installed the latest Adobe Flash and all was well.

More and more firefox is like a virus on my computer. Sometimes I have to go to task manager to turn it truly off, as too many times it just wants to hang around. My computer is clean regarding viruses or malware. It is the Firefox itself.

I thought I'd try Chrome but from this thread it appears a disconnect there as well.

Coigach, thanks for the workaround. It does work and is better than nothing.

But really, at this stage of the game should something like this even be an issue?

I used IE 8 for the first time in a while to access YouTube with no problems today.

Maybe Firefox has had its day, has had its run.

I found this in a google search:

http://www.google.com/support/forum/p/youtube/thread?tid=55e53fe4230a7935&hl=en

When you're at the last stage in exceptions you click block.

This does allow you to watch videos on YouTube without using the pop-out workaround above.

However, you can't log in if you have an account there.

I'll be using IE 8. Thought to post what I found.

I have the same problem but it is also happening with Safari.

I found a fix that works for me. Right click on a Flash Player video and select Settings... in the popup menu. In Youtube the Settings selection is grayed out, so you need to go somewhere else. Try:

http://www.youtube.com/swf_test.html

Click on Settings and you get a dialog box. Mine only has one item, a check box for "Enable hardware acceleration". If the box is checked, that may be your problem. Uncheck it and click Close. There may be different settings and even different Flash Player versions for different browsers, so be sure to do this in Firefox.

Can't be sure where the problem comes from. I only had the problem in Youtube in Firefox.

BTW, I also had a problem previously with Full Screen mode in Youtube, just got a white screen with no audio. Now my Youtube Full Screen works too.