@shivansps: The link I posted above gives instructions to disable all web-based hardware acceleration, not just youtube.
Regarding games, I find that certain games work great and others don't work at all with my 6950's. For example, I can play Neverwinter Nights 2 and Fallout New Vegas while mining without so much as a hiccup. But Civilization 5 won't share resources with the miners causing my system to crash whenever both it and the workers are running. It seems to depend more on the game and less on the GFX card.