K so this is kinda hard to Critique, Im used to critiquing pictures rather than videos..
You don't look too bad for a beginner, I've seen much worse, from people being very far behind in the jump or too far ahead, to terrible hip angles and not giving their horse enough rein. You look pretty good, your heels are down and your timing was good. You can't really ask any more from a beginner Jumper.
P.S for the trot, I would work on getting him to extend and change pace with the trot, makes for a much nicer ride than just plodding along. Use your seat and leg to encourage him to pick up pace as well as slow