Distances, distances, distances. You nor your pony understands where the base of the jump is, so he's taking off from long and short spots to compensate for a lack of knowledge on both your parts. I'm surprised you didn't whack your nose on your pony's neck on the first jump; you jumped too early, the pony put in another stride and chipped it badly.
I'm sure your instructor has the best intentions, but she's going about it in a manner that is going to result in an accident, or your pony becoming sour towards jumping. At 0:36, you yank the pony's head around in a circle, and your instructor is telling you to "kick! Kick!" - no, you should be sitting down, and collecting him up with your seat for the turn. It doesn't seem like she's a jumping instructor; she isn't addressing the very basics: your position, controlling the horse's shoulder and ribcage, and learning distances. She's probably great at some things, but if you truly want to develop your jumping, she's not the trainer to learn under.