Ok i've been able to replicate the problem. Try this: have safari opened and click on a youtube link, it will open another page and then finally open the youtube app. Watch the video for a few seconds and then multitask back to Safari.
It will then only show about 1/4 of the screen before finally locking up and crashing back to the homescreen. Anybody else able to replicate?
EDIT: Was also able to do this clicking on a youtube link from the Facebook app, and then switching back to the Facebook app. The screen looks all wonky before finally crashing about 10 seconds later.