I have a weird issue. Firefox won't play YouTube videos correctly. It plays the sound just fine, but some videos go to half-size and then jump back to fill the YouTube player window. Please click the pic below to see a larger image.
Notice how it doesn't stretch to fit the player window. The video plays and keeps jumping back and forth. Many of these videos are old favorites that I love. They played just fine before.
I have tried (as a fix):
Installing the latest version of Flash for Firefox.
Installing the latest version of Shockwave.
Clearing the cache.
The videos play fine in Internet Explorer and IETab, but flickers in fullscreen mode.
Dxdiag seems to indicate no problems.
Browser: Firefox 18.104.22.168 (don't like Firefox 3)
Operating System: Windows XP Service Pack 2.
AMD Athlon 1.33 GHz
512 MB RAM
256 MB GeForce FX 5200 knockoff (PNY Verto)
So, my question is: Is there a fix for this?