It's a little hard to tell becuase of the video... You look quite nice though. The biggest thing I noticed was your heels need to be down. You have a nice, stable leg, but because your heels aren't down you aren't using your base as nicely as you could. It might also help to slide the stirrup towards the ball of your foot. If you notice in the pictures you posted, the stirrup is almost the the heel of your boot.
I'd also work on your hands. You keep your hands right on the horse's neck. Lift your hands up in the air about an inch and a half (I used to do that too, hah) so your hands are close to the withers but not resting on the horse.
That jumping picture is pretty far away, but it looks like you're jumping ahead a bit. (I still do that!) Try "squatting" down over the jump more. Your elbows are also too bent. If you don't jump ahead as much, your elbows can't be as bent (provided you don't change your release, of course.)
Overall, you look like a nice rider, which a fairly good base. By the way, I absolutely love both of the horses in the videos. You're very lucky to lease such a lovely mare