I don't have video of Mr.D but his photos are all very consistent and show him moving his arms down frist with no movement of his lower body. His lead knee which is pointing 'behind' the ball is still pointing there after his hands are down.
His move down is a vertical drop of the 'Keyston' per Bertholy but Bertholy, I think based on his analysis of tour pros, decided that the knee move should come first. This action of tour pros is one of the reasons I was quite confident in my challenge to show a tour pro that did as Mr.D advised.
