I'm gonna call it a ninja butter. He like, puts one ski behind him, rolls foward and presses the other one, but then pops and flips, and all really fast. Definitly not just a frontflip if you've seen the video.
Dude if you actually look what he does, this describes it.
He lurches forward putting pressure of his weight on the left ski. Then he kicks the right foot backwards, pushing the ski off and back, then he slips forward still and pushes all his momentum on the left foot, and pushing up. Then he gets airborn aqnd pulls the foot in, then rotates the rest as a normal frontflip.