I love it when we can get this kind of near thorough information on weightlifting!
After watching the videos, I noticed that there are two points that I'd like to point out. First is the "high" hip starting position that he advocates, but I think I don't want to comment on that. The second is that, according to him, weightlifters should extend almost straight up, not bending/curving backwards. This last point makes me somewhat confused because I saw several great lifters bend/curve backwards around the top of the full extension, for example:
It's true that the amount of the curve varies among lifters, with some seem to be almost straight (but the torso always leans back a bit). Also when emphasizing "head lead", I found that my body tends to bend/curve more, with a significant speed and hip extension (speed) gain. I know that it's probably because the spine always follows the head.