I realize my lower leg needs a BUNCH of stabilizing, but I'm working on it If I were to critique myself, I'd say my back is really flat, my eyes are looking up, my release is good, but my darn lower leg!
What do you think? I'm a bit aggravated at how terrible my lower leg is, but oh well
Pretty doggone good for a second time jumping!! Good work. Overall, you did well. The lower leg swings back in the most common problem all jump riders fight. Pinching too hard with your knees. When you try to hold yourself in the saddle by grabbing with you knees, it forces your lower leg away from the horses sides. If you relax your knees, you can wrap your leg around the horse's barrel. You want to "hold" the horse with the inside of your lower leg/calf. This will help a lot.
Try walking/trotting in your two point and practice relaxing the knee and holding with the inside of your leg. MAKE your lower leg stay at the girth (you will feel a lot of stretch in the back of your leg).
You are just dealing with the same problem we all deal with.
You're off the a great start. The experts already rang in. All I have to add is to think about hugging your horse with your legs over the fence like you were trying to squeeze toothpaste out his nose. Just thinking about it tends to reduce pinching with the knees and keeps the contact distributed better all the way down the lower leg.
An idea to help you learn the feel of having your leg in the right place is take piece of baling twine and tie your stirrup to your girth (not super tight) this will prevent you leg from slipping and get the feel of it in the correct position.
I would still do a lot more flat work before you continue jumping.
In the first video, if you pause it at frame 0:03, you are getting way, way ahead of your horse and your lower leg has slipped back. In the second video, pause it at 0:07 and you will see the same thing.
Granted, the jumps are low and you are probably just excited to be popping over a fence, but in order to prevent bad habits while jumping, correct position on the flat is necessary. I would have you practicing a lot more two point and work without stirrups at all gaits! Even your posting could use some more practice. I saw a lot of "plopping" back into the saddle on the down part of the post. You need to learn to feel the horse and how he moves and how to stay in time with him.
I probably sound mean compared to the other posts but I see a rider that needs to work on her foundation before jumping. :)