Lovely horse and you can see the connection you guys have in the first video, I would like to see a little more of a partnership in the second video.
First, your lower leg could use some solidifying, it is often too far infront of your hip, putting you almost in a chair seat. This is somewhat related to you using your leg to brace back against your horse as he is travelling quite quick around the course of jumps. This results in your being left behind in a couple and returning to the saddle too soon after the jump.
Speed can be OK in SJ, provided it isn't flat. Your horse certainly has the quicks to get around a course and he is a bold jumper but he is compensating the flat movement with long, flat jumps. Right now over small jumps it won't pose too much of a problem unless you really misjudge an approach in which case the consequences may be severe. Additionally, you will do much better over combinations with an energetic but engaged canter in between.
Perfect practice makes perfect. Get everything right over a small course and it will serve you well when the courses are higher and more complicated.