If you are hard freezing (have to force reset) even after a restore as new, then you may need to have your iPad serviced. Make sure you provide good steps to reproduce to whomever you interact with to set up the service.
My iPad will lock up on video almost immediately on YouTube, ABC, or Netflix if I watch in portrait mode with text in the lower half or on the sides, but it has never locked up while watching video in full screen. I sent the unit back to Apple and they certified it as within specifications (of course). So, I guess I'll be watching all video full screen from now on. I was on MSNBC's site watching video and it locked up, but the video was in a window with text.