OMG! I jerked back watching that!
I go to the gym 5 days a week, and can see that happening at the place we go. That guy was pretty small (Even though I've seen alot of small guys lift weight that surprised me many times) to be lifting that much! GG Spotting!
Edit: I just read the info on the video... IMO, the spotter shouldn't have let go of it so quick. I could see the whole "Friendly lifting competition" thing, but when you're pushing that much weight I'd want to take as much precaution as I could and NOT try a new grip. Good thing he didn't suffer any injuries.