Ron, things can be gleaned from video if the viewer is experienced in what is being shown, and knows what to look for. For most, all that's seen is the effect, with no indication of what the cause is.
A video clip of someone working the "6 directions" would look like someone just standing there. If a partner were to push on the stander.... on the chest, on the back, on either shoulder, on a hip... what the viewer would see is the stander not budging or showing any signs of imbalance. And if the stander were to return the pusher's energy to him, you would see a person standing still, but the pusher getting popped or bounced back.
It wouldn't be very instructive in terms of how things are happening, though certainly the effects would interest people or cause them to say "That's fake!"
Things like that probably happen by "inadvertent activation". And training may be like building a strong belief system.
II still remember very well that very first short instant when a shihan, who previously had felt to me like over 90 kilogram, was on the verge to show koshi nage and was bounced back losing his balance, swaying, dark eyes wide open, instinctively asking "what was that". In fact there was nothing, no automatic body-response at all on my side, much to the surprise of both of us. I had done nothing to him, I just hadn't been ready to comply yet as, actually, I had been lost in an inner process I would describe as cheerily enjoying deep relaxation and a moment of conjoint inertia.
Delusion or not?
Isn't it only natural that everyone feels more than reluctant to write about this kind of experience openly on the net ?