if you were in a motorcycle cage, some force would become fairly constant from the centripetal force of going around and around the cage. If you were sitting on a scale on top of the motorcycle seat, that force might register 3 G's or whatever, but it would stay basically the same. If you tried to push down on the scale in some way you would not be able to increase it beyond that with pushing effort, other then the very briefest impulse which would ultimately result in a slight loss of pressure and then back to stable 3G.
Same in Ski turns, its not any different. Pushing yourself can't be sustained...
The perpetual turn (as long as the gas holds out) for the biker in the cage provides a continuously available platform to push against. Since we're skiing downhill using gravity for the most part for locomotion there will be a reduction in force at turn release, and at some point around that time the platform will become temporarily unavailable. What I took away from the McNichol vid was that by staying heavy at turn release - keeping pressure on one or both skis, whether you focus on the old outside/new inside ski or try to get early onto the old inside/new outside ski - you can momentarily extend the availability of the platform and use it to help keep/move the upper body forward as the new edges start to engage and you move into the new turn. With a push, as an easy way to think of it. Stay heavy at that moment, don't get light just yet. (Basically restating what walkuphill said in post #672 above.)
I think there is a place in a lot of skiing for letting turns just happen organically through a smoothly coordinated series of movements. I think there is also a place where specific active inputs and timing adjustments make sense and are reasonable and effective. Regardless, in my own way I've experienced both in my own skiing. I also see evidence of both in lots of World Cup skiing.