Wow, I finally had a chance to try it out on your bog - awesome! I find myself wanting to make suggestions but only in regards to presentation. Obviously, fixing the whitebalance wouldn't hurt but not a big deal for this demo. Also, it would be cool if there was another smaller view down at the bottom that served several purposes - to see what's behind you and to also serve as the control to rotate the camera and indicate directions such as North. Sorta like a flight game which has a radar display to help with what's behind. But once again, these are things I thought of as I used it.
I honestly believe you have opened a new door in underwater videography (or perhaps videography as well)!
I have many questions but mainly I don't see much of a visible boundary/edge between the frames from the separate cameras. How did you manage to get their exposures so closely matched - or was it mainly done in post? Also, is this with GoPro's or something bigger? How many cameras - perhaps four - or more?