1 Overall: My first impression of this rider is that she’s kind of a seat-of-the-pants rider, but she hasn’t gone through the American equitation system.
Her foot is what we call “too far home” in the stirrup: The iron is too close to the heel and not on the ball of her foot. She also doesn’t have any weight in her heels in the air, and she’s spurring the horse in the air, maybe by accident. She’s reaching for her stirrups as well, which is causing her to pinch with her knee and not have contact with her calf. This has caused her lower leg to slide back. I suggest she shorten her stirrups and work in two-point and without stirrups on the flat to strengthen her balance