Both momentum and kinetic energy are ALWAYS conserved. The MC had so much kinetic energy and the car so much inertia to stop the MC's movement, that the energy had to go somewhere. It expended itself by going upward and gravity gradually dissipated the KE of the motorcycle (with a small amount going to swinging the cross light.) While momentum is a vector, kinetic energy is a scalar and can change directions easily. In physics class, this would be called a classic "inelastic collision" with some energy going into "deforming" and moving the car a little and the rest of the energy changing direction and hurling the MC upward. Issac Newton, if he came back to life and viewed the video would probably just yawn and say something like "So what? I told you this is how it works. Now, where can I get me one of those fast 'mechanical horses' the guy was riding? Is this some kind of sorcery?"