Was he going for a double backflip? I mean, he was out cold mid-air and still had plenty of rotation for a single backflip with no tuck or anything.
Getting KTFO sucks. My mountain biking days ended abruptly when I headbutted a rocked after going over the handlebars at about 40mph. That helmet saved my life but got cracked in half. The only reason I still have my teeth is because my tongue acted as a mouth guard. I still chipped 3 teeth... after biting through my tongue.