If you are wanting a western seat, lower your stirrups a bit; they're really short.
As for the leg movement; it appears that you have a weak/untrained leg - lots of posting at the walk with and without your irons and practicing two-point position at the walk will help that a lot!
When you are posting, it appears that especially when you are on the left diagonal, you get left behind in your post - - be sure to allow the horse's momentum to pick you up out of the saddle. ;)
A good tip for catching the correct diagonal is to look at the outside (railside) leg, and make sure you are sitting when it is back - - which will leave you no choice but to rise when it's forward
In the canter, it looks like you are really stiff from mid back to knee -- loosen it up a bit and let your hips go to work on the saddle...it'll make for a more comfortable ride.
Also, i'd suggest moving to a non-leveraged bit for the english work...more comfortable for the horse ;)
Keep up the good work!