First off, you are really a very nicely matched pair! I think the judges will like you alot.
I dont' do HUS, so my point of view is more general as to what is basic good equitation. I think you post very nicely. Super nicely. Your hands were the tiniest bit "busy" and I only noticed it because you had your wrists crooked . (I mean, that the wrist goes inward while your knuckles face outward), and your fingers are too open at times.
You have a very typical hand position with your hands low and far apart, and a mildly overstraight elbow. To me, (my opinion), this doesn't look good. I would put a bit more bend in my elbow, raise my hands a bit and for sure, bring them closer together.
I saw one point where you transitioned down to a walk and the horse raised his head and you "fiddled" his head back down again with your hands. If you had prepared him more with your seat and a core muscles, he might not have raised his head when transitioning down, and you would not feel the need to put his head back down.
So, "hands together puts horse together". Don't pull or fiddle his head down. Straight line elbow to mouth , no bend in the wrist. Look up and prepare him for each transition first with your seat, then with the rein.