I cannot stand on one foot without joining structures with the pusher. Nor can I stay at 90 degrees. No one can, without using what I showed in video 3 (mental suggestion).
If anyone can do this, please post videos! I've heard of these things, but when it comes to showing them, strange enough no one can.
Hmmmmm.... well, I tend to show how to do this at most first workshops, Chris. I don't use that example, since it's just a beginning workshop, but what I tend to do is have a partner push on the person's chest with one hand and the "nage" stands first with one foot forward and then shifts into two feet parallel. I.e., it's a reasonable approximation for a first-time attempt; the principles are the same. Maybe someone can make a video of it and show it.
I've explained this type of demonstration a couple of times on this very web-forum, IIRC. And realistically, once someone understands how to do these things, "aiki" isn't too far away. Well, understanding isn't too far away; expertise comes with practice, as in most things.
All I'm saying is that "no one can" may be a bit of exaggeration. It's all in knowing how. One of the things I've suggested numerous times is that people estimate the size and direction of the incoming force (in that Tohei-related photograph) and back figure the necessary force vector that is required to put the two people into stasis... and the how-to becomes obvious.