Looks like Apple have finally done away with the glass back, that looks like a very well built phone. That test shows exactly the reason why I didn't want an S3 though, it's got a flimsy plastic back which just reminds me of an old Motorola or something, and I've dropped my One X countless times with no damage at all, and all I used is a £3 gel case I got off Amazon.
The guy in the video even says 'it's just cheap plastic so who cares' when he drops it and the back comes off.