I agree with what ohhellneely said - you need to be more in charge. I am assuming that the horse is a lesson horse, but you are a strong enough rider to be in charge. The first two videos he seemed a little sluggish, im guesing both of you were tired and that this was towards the end of your lesson? This is where I think you look your best, you are sitting up, your leg is very nice and still and your are staying with him more. The last two videos are a little unpolished. He seems to be in control of the distance, pace, etc. I like that he looks more lively in these videos though. For you, I would sit down on your butt more. Instead of overdoing the release and throwing the reins away, hold onto them more. At one point I paused the video and your hands were up by his neck - by holding the reins a little tighter, I think the landing will be smoother and you will be in more control. The bigger releases are essential for beginners as they are still learning how to balance. Sorry for the long post, im a wee bored!!!