This is a good example of how important the set-up is in how the golf swing functions, and how posture and balance can determine how the body moves once the swing gets started. Mark has exaggerated knee flex for sure, but most importantly he starts with his weight well back into his heels. As soon as I see a set-up like this I expect the general movement of the pivot to be forward toward the ball, and keeping the hips in the box almost an impossibility.