In the first video, if that is what you mean by staying 90 degrees in that situation, I stand corrected. You can receive some force in this manner. When you asked the first time, I thought you meant a full force push (as I showed in my second video). To a degree, everyone can resist some force this way, but the amount is minor.
Wouldn't that also depend upon, say, what Mark knows versus what you know, debatably? If someone knows how to manipulate forces, he can train to withstand a lot more force than you'd think, in a static situation, although no one can withstand the onslaught of a runaway 1955 Chevrolate pickup truck, I agree.
The point is that if you know how to do this trick, *and* you can do it in static and dynamic situations at will, you can manipulate an incoming force and not only negate that force by 'grounding' it but also can train to manipulate the attacking force so that the attacker's force works against him and helps to throw him. If you understand what I just said, then you can begin to understand what Inaba Sensei, Ueshiba, Tohei, Shioda, and others were talking about when they were discussing the importance of "aiki".