Damn, those videos are so amazing. I'm simultaneously inspired and depressed as I have not "go-proed" anything cool in a while. I'll try to focus on the former.
I'm actually 2 pieces of equipment away from having my own badass full set of Scuba gear. Got BCD, Dive Computer, and have 7mm wetsuit and regulators on layaway. And I promised I'd take my GoPro (with my dozen or so attachments) with me, every time.
might have posted this, and it's way boring compared to the above but it proves I'm not a total loser (i'm barely visible next to my dive buddy, but still, GoPros are the Man toy of the century!):