I'll try to help you see a couple of thinsgs, though.
In the first jump, you can see how she starts her jumping movements a little bit earlier than the horse does. She puts herself "avant le cheval". As a consequence she also lands a little bit before the horse and she hangs on his mouth for a couple of seconds. It's very slight and we just see it because of the slow motion, but a sensitive horse can get tired of that. The third day Troy refused to take a jump because she put herself too forward in a double jump and he knew what was going to happen.
I have just watched it again and I can very clearly see the "avant le cheval" on the landing. And she pulls back on the reins, at the same time looking up and ahead as if already going to the next jump in her mind. Of course, I have no idea if she is doing the correct thing. This is what I see her doing. But I can see that Troy seems to dislike it as she pulls back. He shakes his head. This is because of the bit, I presume. She pulls back to make him stop and it hurts, and he doesn't like it. I understand that. Personally, I don't like the use of bits, but I've been told that inexperienced riders like Charlotte rely on them. I can see the proof now. Charlotte does rely on it a lot! Of course, a less experienced horse might not mind it so much, but Troy probably knows exactly what he is doing and wonders why this girl is telling him so harshly how to do his job!?!
In 0.49-0.50 you can see how she doesn't use her legs. She takes the turns only with her inner hand (what do you save your external hand for, Charlotte?) and you can easily see the stress she puts on the horse mouth and the pain and surprise in the white of horse'eyes.
It seems like she turns (using the inner hand, as you say) and then she uses that other hand to pull back. It's like, just after a jump, she pulls back, he rears his head in pain, she is turning him with her inner hand, and then he dips his head (in pain?) and she pulls back with external hand to get his head up again. ?? I notice the whites in his eyes. I didn't know that was indicative of stress.
In that same jump you can see how she loses her balance while jumping and doesn't put her weight on the stirrups. In some of the jumps she has her weight perfectly put on the stirrups but half of the time she looses balance. As a consequence of that lack of control of her legs you can see her feet travel to the back of the horse and and then make a huge movement forward and when she lands she sticks her spurs on the horse flanks.
Look at the constant movement of Charlotte's ankle and how her legs never stay still, to the point that sometimes her feet are before the girth and even before the horse's elbow.
If you want to see what I mean about how the horse is scarred by Charlotte's constant use of the spurs, you have a good look at 2.16,. Charlotte legs are forward and you'll see a white mark in the place where her spurs usually rest. Troy has a similar mark in both flanks. You can also see how the jump she takes after 2.16 is a much better jump than others. She stays at her place centered and balanced, the feet don't go to the heavens, etc
Also, no wonder that her hand is so hard since she holds the reins like a little kid. Holding them above the small finger would give her a less strong more precise grip.
She really seems to lose balance in the jump that starts at around 2:42. I see the feet move a lot. I also noticed the spur marks. And the tight reins, totally. Even I know that all horses hate that because it's confining, and they hate any kind of infringement.
Thank you for guiding me through it. I have to watch a few more times, though, to really understand. I enjoy it, however. It's fun to take Jumping 101 with Trep at TRF University.