I agree with Waresbear ( I often do) that you look like you are having fun, and honestly, you are doing just fine. The thing that you most need to work on is becoming better able to not pull on the horse's mouth. I mean, since you are stiff , your elbow is not allowing for the hrose's movement, thus, when you bump around, it's coming out through your hands, into his mouth. You can see that your hands go up and down with each rise and fall of posting, which is not correct. YOU should go up and down (well , it's more of forward/backward) but your hands need to stay in the same place. How can you do that? Your elbows need to open and close, like hinges on a door, so that your hands DON'T move around. This is how a person can separate the movement of the body from the movement of the hands.