Hi Gary -
I never mentioned the shoulder or hips initiating any movement. The body moves as a relaxed, integrated unit, not piecemeal. That idea was drummed into my and Mary's heads for years by Maruyama Sensei.
There is no disconnect because if the shoulder disconnects uke will run right thru you.
My experience tells me that maintaining internal connection within yourself, your oneness if you like, is incredibly difficult to maintain as you move within a simulated environment where one attacks another within a training environment.....the problem being that one doesn't even sense/feel when they fall in and out of stability as they respond to the attack. Working on a daily basis within one's friendly and comfortable training environment doesn't help to bring these moments up to a level of awareness as you move through your training. It is also clear that dropping in and out is part of the reality of the relationship between people as they move together. Moving together in a friendly environment makes it less likely, over time, that one's awareness within oneself of the 'openings' presented by them within the movement come to the surface of their awareness.
Talking about the movement shown by Endo Sensei in the clip, for my part I would want to feel what he is doing as he is doing it to understand his level of connection within himself, where his movement is generated and how he is maintaining the bridge with me.