Your horse is lovely!
Anyways, here's what I saw:
1. You have a too much foot in the stirrups. They should be on the balls of your feet, not the center.
2. You seem to be bracing against the stirrups. The concept of heels down is more realistically 'toes up', meaning that instead of jamming the weight into your heels and bracing you should be stretching your toes upwards to rest against the stirrup. It's a generally more advanced concept as most beginners are taught to put the weight in their stirrup (to teach proper leg placement and build muscle). However once you've reached a certain level it prevents your leg from being soft and consistent against your horse's sides, stiffens your overall movements, and locks your leg in an noneffective stiff position.
3. You are jumping ahead of the motion. To fix this, you must sit tall and quiet on the approach, give your horse his head, and let him come up to you. Only then should you fold forwards and meet him at the halfway point. To help with this, count the strides in your head going into the jump (one, two, one, two
) or sing a song with a steady beat in your head (row, row, row your boat
). Don't anticipate and 2-point before your horse's feet leave the ground. Mid-air, try to stick your butt back a little; it will help keep it centered over the middle of the saddle.
4. Approach in full seat. The fact that you are over-jumping and your horse's constant short/long spots (at least, that's what I see from where he is taking off) leads me to believe that you are approaching the jump in a half-seat that restricts his ability to find correct striding. It is better to practice approaching in a full seat with a gentle rein because it will help both you and your horse feel the rhythm and find a great takeoff spot.
5. You are also sitting down a tad too early. Over the middle of the jump, your seat should still be hovering slightly in the air and your hip angle closed.
6. Where is your release?? Over the jump, your hands are still glued to the withers. Reach forwards to give a nice open crest release. Your hands should come about halfway up the neck. This will also help your horse find a better takeoff spot and stretch nicely over the jump. At the moment you are restricting him.
Overall, however, I think the two of you look very nice as a team. Some good exercises for you to practice would be jumping grids and single jumps with no reins, riding with no stirrups, jumping with no stirrups, and (only if you feel completely confident and trust your horse 100%) jumping with no reins AND no stirrups. Hope I was helpful