I'm sure the instructors here can give you a much more detailed breakdown, but some things I saw right away:
Rear knee is collapsing inward. Bend both your knees and keep them rotated out, not buckling inward.
Shoulders seem a bit open, might be because you are holding the camera, this could be causing the above. Stay square with the board.
Maybe be a little more dynamic getting your hips and ankles into your riding, will help with edge control as it allows you to weight/unweight the board more precisely and get cleaner carves.