Heres the things I see:
-hold your reins with your thumbs up and pinkies down. It looked like you were holding them like you were playing a piano
-try to point your toes more forward- parallel with the horse or pointed a bit towards his nose.
-I didn't see a helmet!!!! Its your choice, but I personally wouldn't want my brains smashed if something were to happen. My barns require a certified helmet whenevermounted
You had a pretty strong seat and looked confident and as if you were having fun. Legs looked good (i'm always having trounble with those) and you look comfortable.