As mentioned above hard to say a whole lot from this video...BUT this video does definativley highlight one major issue with your skiing. If you watch your skis, they turn alot very quick...then just skid....basically, you got big twist, skiddddddddddddd, big twist, skiddddddddd.
This is baddddddddddd.
In order to derive more performance, more efficiency, and more control, your skis should turn at a (relativley speaking) consistent rate. With that big twist, it is impossible for you to carve or edge effectivley. In essence you are doing linked hockey stops.
To correct, think about your timing...SLOW the rate the skis turn at intiation, but keep steering them throughout the whole turn. So the action is progressive and constant from the top of the turn to the bottom.
Other issues can be seen in the shadow (ie appears to be a lack of any flexion/extension) but watchign the video was making me sick so I couldnt verify.If we had a shot of you skiing, we could link cause/effect better. But sometimes your twist/skidd issue, is just timing as I wrote above.