2 thumbs together is weaker than covering the thumb with the palm in my experience.
Chris, I agree with you that getting their center of gravity to move with you and the wrist is the way to go for real - and I posted the same sentiment myself. But what I'm confused about is why if you know some level of that kind of structure that you would be arguing leverage at all. Leverage isn't going to get their center of gravity moving with their wrist. You can draw them into your structure from the front or for the outstretched position you can do a "pure" weight transfer to break up their structure a bit and then draw them into your structure. And once that happens you'll have leverage on them, but focusing on the cart before the horse ain't gonna cut it.
Mark, not looking to pick on you, but the second video isn't selling it to me becuase it shows you dumping your center down your front a lot from seconds 9-16. Are you getting a lot of intention across your body to maintain resistance? I can't managae that very well unless I have my spine straighter.
I was just playing around with a few things. Didn't really want to cover kote gaeshi in all situations.
Plus, I lose structure a lot when trying this stuff in less than static training. So yeah, I'm working to keep structure while moving and having force applied in a dynamic way.
That is the very nature of why I paused/stopped/put on hold my aikido training. It's rough to try to keep structure when working on dynamic technique driven training. At least in the beginning. I couldn't have done anything like those two vids a year ago. I'd have lost structure instantly. So, things are progressing. I'm hoping that in another year, I can pursue active aikido training again while keeping structure in dynamic training. We'll see how that shapes up.