Relaxing the downhill ski with early weight transfer to the uphill ski prior to initiating the turn - most if not all of the weight on the outside ski throughout the turn - a tall stance and balance centered over the foot - these are what constitute the "breakthrough" (for skiing on firm snow) as I perceive it. (He gets into other techniques for moguls and powder.)
Regarding the narrow stance, I'll quote Lito...
"I ... caution you against what I consider an old-fashioned and counterproductive version of a narrow stance on skis. I don't want anyone to jam one foot next to the other or worse yet - to jam one knee in behind the other - I am proposing a functional, relaxed, and dynamic narrow stance, balanced primarily on one foot with the light foot actively keeping the other ski more or less near, more or less parallel, to the ski you are standing on. ... A narrower stance makes it easier to shift our weight from foot to foot, from ski to ski. ... More result for less effort."
In the video on groomers I see some skidding in Lito's skiing at times, but it seems intentionally blended to achieve the desired result, which perhaps might be easy, relaxed skiing. I also see him carving more sharply at times, with more flex and counter ("dynamic anticipation" in Lito-speak). He seems perfectly capable of putting a ski on edge and keeping it there if he wants to. Is it necessary to carve cleanly all the time?
Billie Jean King said of Federer the other night (paraphrase) - "He's an old school player with modern power - that's why we love him". Federer has a one-hander, and doesn't use modern/extreme grips on either side - he does in a sense have an updated, more athletic version of a classic game like Laver's. It's also about the way he blends his play with different strokes and all court movement and tactics that make for his beautiful and (typically, though sadly, not this weekend) highly successful game.
Can't skiing be more like tennis in that regard? Is it, and I just haven't seen it (yet)?