Like RicB I have no desire to argue this point for pages so this is very likely my last post here although I will respond to BtS or zenny when they get back from exploring this stuff on snow.
In response to your first sentence. Say what, i just don't get what your point is here.
The point is that he didn't make a rotary or edging video. But to create the maneuver he wants he uses them and the question seemed to be how he made it happen
Second/third sentences. I know precisely what will happen to his com if he releases it it will keep moving in the same direction at the same speed. So if you are side slipping and your feet go slower than your Com, where will you Com go? Someplace over your edges downhill I bet. And just how is this speed differential created and then reversed to get the feet downhill from the body? Cross-over isn't necessarily going to happen because the skier and the skis are going in the same direction at the same speed. The skis slow down in relation to the com. How/Why? Yes, I know that the skis are moving sideways but it make no difference. It does if they slow down in relation to the com due to force (thus my rambling of rotary, edging, etc, etc - the force). (This is a great example of what you describe in your last sentence. You are "looking for ways to get across more quickly and accurately)/ See above questions about the how.
Forth and fifth sentences. I'm connected to the world through my skis so that provides all the reaction force I need to rotate my body. That's what I'm talking about! Then it wasn't very clear.
Sixth sentence. The mass of my upper body provides plenty of resistance to pull my foot back. I highly doubt you won't activate some part of your body that you weren't activating before you pulled your foot back. Pull my foot back in the low friction environment of skiing using only the mass of my body for reaction? Do it all the time. Foot moves back a lot the body moves forward a little. Try walking without using any muscles but the leg you are moving. What does walking have to do with what we are talking about? Pull the foot back, simple singular movement easy to explain. Walking? There are books upon books written on gate mechanics. Not nearly so simple.
Last sentence. In this situation just having the com cross-over isn't going to cut it, without precise manipulation of the skis all that will do is introduce to a fall called a 'slam dunk' Yep and I never said it would. I mentioned the fact that other forces come into play after he initiated with a foot pull-back like edging, rotary, etc, etc. But the foot pullback initiates nothing it just changes the relation of that foot to the body allowing things that he is doing before and after the pullback to spin the skis around.
And finally, God, I dislike the term topple. When I ski i don't have the time to wait for my com to topple over to move it into the new turn. I'm looking for ways to get it across quicker and more accurately. No really? Isn't that whole freaking point of skiing? If you think you are perfectly balanced while skiing 100% of the time you have another thing comin'. I mean, why would you be "looking for ways to get across more quickly if you were so balanced to begin with? I'm not pointing fingers at you, but that's skiing. Call it what you like. In other words, we all 'topple' some of us just face-plant. Actually, I'm seldom balanced when I'm skiing. Centered over the tool, yes. Manipulating the forces I can generate with the tool to propel me where I want to go, always. Waiting for the puny force of gravity to 'topple' me across the skis, seldom. There are ways to get across the skis quicker.
You have the potential to become a good instructor and your curiosity will lead you to deeper understanding of how skiing works but you aren't there yet. You have a few years experience many on here have a few decades. Time is a very important factor in training your eye to see what is happening and understanding the how and why of what is going on.
Yes, he pulled the foot back and he turned, but he didn't turn because he pulled the foot back. Pulling the foot back was a very helpful move to make the maneuver happen but it wasn't the cause.
One last point. This vid was made so an intermediate skier could watch it and then go on snow and reproduce it. In that respect it's one of the best I've seen and I have no doubt that for that intermediate skier pulling the ski back would swing the skis down hill because they expect and want that to happen. But take a bunch of very knowledgeable ski instructors and we will see a lot more going on than just that foot pullback.