Thank you, gonz! And thanks TomB, fltlndr and coach13 for your very perceptive comments.
I agree completely- the back seat and skidding the initiation (related, of course) have been long-standing problems that I think I am beginning to get more of a handle on, especially after four days in a row of world-class coaching. I worked at the end of last season with Ric on getting more centered on the ski (and my feet), and worked quite a bit with Weems on initiating the turn from the shovel of the skis, allowing them to bite and start the carve. In looking at the video myself, I noticed that there were some turns where I seemed to get it just right, and others (most dramatically in the first turns of the first sequence) where I looked just awful. I guess this is just part of the process of integrating new movements. Anyone else? (note to Weems- to arrest ocular hemorrhage, apply direct pressure).