Guys, do some reading. That was not his hand, just his glove. Check around online, you'll find the guy's name is Brock Davidson and it was a nitrous explosion that blew a part of his airbox apart taking his glove with it.
Mixed reviews, one guy says hand, one guy says glove, one guy says sternum? Either way, wasn't fun I'm sure. This is actually a better video but really off topic..