It's pretty interesting stuff. I haven't had a lot of time to work on it myself because I'm right in the middle of our golf season here in Kansas. I'm not comfortable trying to teach it without having it mastered myself.
What's really thought provoking personally is I do a lot of this stuff already. The left hand grip, left shoulder up and back some, left arm bends a little coming through impact, left, right, left step. I've never had live lesson in my life. Lots of cussing and discussing of the golf swing, watched videos, and a million golf balls. I picked the game up in my early 20's and 20 years later I hit it pretty good.
Having this info 20 years ago would have shaved a lot of time off of getting where I am now though. Well done video Brian.
One thing I've noticed with my left hand grip, not much angle, is it is very easy to shut the club face down through impact. Sometimes to much. My misses are shut face misses off the toe of the club. I hate that shot. When I time everything up the shots are really good and the distance gains are really good too.
If you have any insight on how to avoid this I would really appreciate it.
Edit to add; It never really clicked with me before and I don't know why but tumble and handle drag are completely incompatible. Something about the way you described tumble in this video put that together for me.