The way it looks like that guy did it is lean forward in air then lean back/cushion the landing enough to stay on the back wheel, and accelerate from the leaned back position. More or less a wheelie jump I think. If you lean forward too early you don't get enough traction on the rear wheel to make the jump.Man Frost Bite can go to hell.
I finally managed the third checkpoint after 150 faults only to run out of time at this jump
http://www.youtube.com/watch?feature=player_detailpage&v=Ht6wZPzc62Y#t=160
how?!
way harder then 3rd checkpoint
You can do it in separate steps though. You can try landing with the front wheel in the gap and rocking your way back onto the rock, then try the wheelie jump (or whatever method) from there to get up.