I wonder if the creator of the video thinks one edges the outside ski by everting the outside foot? That would lead to what he describes, especially if the boots aren't fitted just right. Don't evert that foot...roll it up on its inside edge. Instead lighten and invert the inside foot (roll it to its outside edge). Keep the outside leg and ankle straight and strong. Tilt the lower body to get the skis up on edge.
Here's Stefano Gross showing how it's done.
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Think @Dr. Kim linked pronation with postural response and platform angle (for grip) through these 3 slides.
Why give up platform angle (and grip) at the ankle?
Patrick Baetz shows how it's done.