I had the pleasure of working out with Yonamine Sensei for about a week at one of George's Thompson Island camps (circa 1983). Among other wonderful interactions, he taught me Hamahiga no tonfa which I still do and teach today. He is definitely a Uechi legend. He's everything you say he is, and a wonderful human being to boot.
Mark is a beast; that is for sure. That's a Marine through and through. We've interacted on and off through the years, and I finally got a chance to meet him at one of George's Massachusetts Maritime Academy camps.
In short... Yonamine Sensei and Mark are doing this demo at his test
because they can. As you stated... a teacher who works out with a student for many years knows a student. There's no better person to bring the best out of someone. That's exactly what I witnessed in that video.
It's also worth noting that Newton's laws apply. When a sports car meets a truck... Just saying.
P.S. Thanks for supplying this, Mark.