Carver, very nice.
One foot skiing is actually a step beyond the skills covered in the Your Ski Coach Building Blocks Basic Balance DVD you're currently working on. Be sure to not bypass the more fundimental lateral and fore/aft balance skills the DVD teaches. The Advanced Balance DVD goes beyond what you're doing here, with an assortment of fore/aft variations, and the foundation balance skills learned in Basic Balance allows for success in performing those variations.
Also, you said your focus was on fore balance and turning with the leg only. Your fore looks pretty good. The leg steering is a bit limited. There seems to be a lot of carving going on. Nothing wrong with carving the drill, in fact it's good to be able to do. But if your intent was steering, then carving is a fault. You need to learn to able to do both. Have you started working on Building Blocks Basic Edging yet? It will help you embed a broad range of steering skills that you can then take into this drill. You should be able to steer this drill, doing either narrow track or wide track steering, and even changing back and forth from narrow to wide during the course of a single turn.
Balance and edging skills like that will help you immensely in your overall all-mountain skiing. As example,,, bumps. Having the edging skills to go through the full range of narrow track to wide track steering allows you to easily manage speed as you look ahead and pick your line. And combining it with the lateral skills you're working on here will allow you to do it on either foot, as need or desire dictates.
Well done so far, Carver,,, but keep expanding the skill base. I'd like to see some video of you doing this drill with steering, both narrow and wide track. And in turn shapes up to 90 degree.