This video of Dan John describing the proper way to do some Olympic lifts may provide some clues. Be warned, it's 50 minutes long. Towards the end, Dan is showing someone proper squat techniqe and he walks the person through two ways to do a long jump-- one with the legs bending, and the other with locked legs powered by the torso. The person jumps much further with the second version.
I don't think the motion Dan describes is as subtle as the internal jump, but I think it does provide some pointers as to where the engine is and how to become acquainted with it.
I'll second that, it's good "#$t. Guy has a good understanding of biomechanics. Now if he could only take it a step further!