John,
Thanks for taking so much time to illustrate your point. I do see what you mean, although the term "vibration" is one of those misnomers (IMO) that cause much misunderstanding. Try as I might tho', I can't come up with a good alternative

.
Choka tsuki from Hachiji dachi is an interesting option to illustrate your point since mobility of the hips is very limited in this stance and therefore speed and power of the punch must either come from "core" muscles imparting a short but powerful twist to the shoulder to throw the punch, and/or the undesirable combination of pecs, triceps and anterior deltoids actively propelling the arm. Trying to get beginners to use the core to throw the arm and not push the arm in choka tsuki seemed one of the hardest things to teach.
Makoto wrote:
http://www.youtube.com/watch?v=-a_0dc4aK08
This type of hip vibration is actually close to the double hip idea. I like this kind of action. I think it is very effective.
Yes, I see exactly what you mean. I notice the drop of the shoulder at the beginning of each punch, indicating a relaxed shoulder.
Makoto wrote:
http://www.youtube.com/watch?v=R1PZbInSsyc
jump to about 5:40 to the end to see what I am referring to here in this video.
Agreed, this is awful, in the left punch at 5:41, the hip is coming back before the arm is half extended. Even worse is the arm and hand position. In the right punch at 5:40, the arm comes across the body first and then the fist drops down, so the punch ends up a sort of flick.
Thanks again
Geof