Re: Video tearing in fullscreen (flash)
Sorry, i can't help with that situation, maybe someone else can.
You can try the HTML5 experiment that YouTube is running but that won't help with other Flash issues from other websites.
Flash is renown for being problematic in Linux, especially at fullscreen. It runs great at fullscreen on my system although I bought a system that was tailor made for Linux, to some extent.
Best of luck.
The difference between wisdom and foolishness? Wisdom knows how foolish it is.