This nicely explains what Comprex was talking about in part of another thread that was moved here, my name put on it. (Not an instructor, obviously). I get the idea now, but remain concerned about the biomechanics of this.
What the video shows is the big toe being actively dorsiflexed (and the foot supinated) by the Tibialis anterior and the Extensor digitorum longus. All exagerated for instructional purposes. Fine, but these are comparatively small muscles that are designed for endurance (lifting the toes reflexively during heel strike) rather than power (pushing against resistance). The most powerful I've ever seen are in ballet dancers, who must occasionally keep the foot dorsiflexed for several seconds, and they're still only a few cm in cross section.
I'd guess that if you or your students try actively dorsiflexing over and over against a stiff boot, weighted by boot, ski and binding, you'll end up enjoying some of the best cramps in your living experience, not to mention risk of eventual inflamation of those long tendons that are supposed to flex well above the dorsal foot surface, now also prevented by the boot. Thus the discussion in that other thread about how strong our anterior calves should be. (The answer: Never will be strong enough.)
So I realize that once we commit the movement to muscle memory, it'll be far more subtle. But that won't make the biomechanical problem go away: You're still using active contraction of very small muscles and very exposed tendons over and over to accomplish a large movement against a fair amount of resistance. I don't get it: Once you learn it fully, do you stop actually firing the muscles? In which case, why is it relevant? (But like I said, obviously not an instructor, so obviously missing several points.)