Flat: You leg looks ever so slightly forward (there should be a line from your shoulder to your leg), and your heels could go down a little more. Overall your flat is almost perfect except a few little things you can work on. Wish I looked that good on flat. LOL. I'm always leaning forward.
Jumping: RELEASE! RELEASE! RELEASE! Move your hands up towards the middle of his neck, and grab some mane if you need to so you don't fall backwards too early on landing. Your leg falls back a lot, work on strengthening them and you should be all good. Other then that I don't see a whole lot wrong, your looking ahead, and you appear to be out of the saddle the right amount. Good luck.