I'm going to take issue with that example for the purposes of bringing up a potential pitfall with assessing internal training methods and demonstrations.
The demo is interesting in that it illustrates one of the difficulties in internal training - differentiating what people say or think they are doing and what they are actually doing. Regardless of his level of internal development, what he is doing to move his uke requires no particular internal skill (if we are defining it as jin or ground force or some aspect of being able to use the ground and the entire body to transmit force), or perhaps minimal internal skill. When they grab his wrists, and he demonstrates how to move them using his body, what he is doing is a small movement of his own forearm (like you would do in suwariwaza kokyu-ho) to change the angle of their wrist so that it is physically impossible for them to be able to apply an effective force with their grip. Because they are trying to still hold on with strength, they have to disengage their shoulders (raising them) to try to maintain an angle with their arm that allows them to keep their grip. Disengaging the muscles that keep the shoulder blade down effectively nullifies your ability to transmit force between your arms and torso (unless, I suppose, you are freakishly flexible and strong). Coupled with the fact that the situation (demo being done by a shihan) calls for them to keep on trying to hold on no matter what, they have no choice but to be moved around.
I'm saying nothing about his actual level of skill, as I've never met him. I'm just saying that even if he is fantastically skilled, what he is demonstrating is not what he says he is demonstrating, and that what he is demonstrating does not require the use of the whole body as he says. He does say how you have to get their shoulder high but doesn't seem to connect that with "using your whole body". You achieve that by the small forearm movement coupled with your partner's agreement not to let their grip be broken.
Having said all that, if you actually have internal skill, the trick is probably easier to do, but it is not required. The "four-legged animal that you are in control of" skill would also be helpful, but again, not required if your partner a) can't apply an effective force due to the awkward angle of their wrist and shoulder, and b) is agreeing not to let go.
And of course the difficulty is this - does he know that what he is demonstrating is actually not what he says he is demonstrating?