crashing while playing video or youtube is due to driver bug and it will be probably resolved in 11.7 drivers.
Ahh! I've been losing my mind over this. Glad to hear there's nothing I can do about it... after wasting a few hours fiddling with the flags.
You can - turn hardware acceleration (HA) for the flash player or for any other program that uses is - Firefox has its own HA for displaying the web pages, video players has it also, etc.
Google how to do it - it's mega easy.