It's hard to tell from the quality, but it almost looks like your stirrup is too long. It doesn't look like you weight's in your heel.
To me it looks like you're rocking/pumping your upper body in the canter. It's like you're over riding as I am really drawn to your upper body movement over the fences. What I'd like to see if I was your trainer is you lifting your hands... 3/4 of the time they are down on the withers. It will help support and lift your horse before the fence, and your shoulders won't be pointing down till you are in you 2point.