You have shown that you can ski fast but now you need to show that you can ski slowly. In your run down the fall line, your stance varies widely with marked variation in the distance between your feet/skis. This clip shows the widest separation which happens as you try to reduce speed by extending your outside leg into a skid.
The ideal width between your feet is when your legs come straight down from the hip sockets, about the same width as when you walk. I would suggest that you begin at slower speeds to enable yourself to maintain this stance without the need to make the braking movement illustrated in the clip. Even begin with simple traverses across the hill while carving your skis to a stop and maintaining the ideal ski separation. Once you adapt to this stance then begin to make long radius turns while skiing slowly enough that you avoid the need to skid to slow your speed.
You can then begin to incorporate a pole swing to begin your turns and to begin some flexion and extension to improve the static position that you now have.
It is much more difficult to ski efficiently with good technique while skiing slowly than by bombing down the hill. It would be a good challenge for you and would allow you to concentrate on improving your skills. You can get by with a lot of bad habits while skiing fast as evidenced by your video.