Great post; now I have to duck out for an hour. I think it's quite possible to flex knees only, and believe that is what is happening, but I am willing to discuss and be talked out of it too. Riddle me this; what if the hip flexion was preloaded? to be continued...
Ok. I will play along a bit. Is there preloaded hip flexion? Sure. I have no problem with that at all. But in this picture, what do you see as the difference between pic 1 and pic 2? I see knee flexion as she lowers. I see her torso staying at nearly the same angle. Therefore there needs to be some flexion in the hips in order to maintain the upright torso. Do you agree?
Going back to the Bond's clip, it is obviously not a standard squat motion. While his knee is flexing, his COG is also moving forward some (while trying to stay back). So from a visual perspective, his rear knee is moving down and in. Are you suggesting that the level of hip flexion does not change because of the down and in action of the rear knee?
Furthermore, are you suggesting that this motion will not vary based on the individual athletes level of strength, flexibility, etc.?