Thank you for linking that video. I watched it twice and plan to watch it again.
I popped in on my TGM instructor yesterday (my grandsons graduation ceremony was close by) and we just sat down together and discussed Homer Kelly and his book. (I had prepared several questions that dealt with parts of the book that I couldn't wrap my brain around. ie 7-3- Right forearm alignment)
He showed me the diffence between dual horizontal hinge action and angled hinge action. He showed me that the left wrist rolls to verticle to the plane through impact.
He also worked with me on how the right forearm is in line with the clubshaft at the end of the backswing with a flying right elbow. (7-3) That is going to take some work getting into that position.