On the second video, she makes a bid to the out fence of the line because she’s getting there on a half stride. She looks like shes naturally short strided and she needs to motor along more to open that stride enough to get there on an even pace instead of chunking around behind your leg then making a bid to a decent spot.
Count, sing a song, something to keep the same canter stride 1-2-1-2-1-2-1-2 jump-land 1-2-1-2-1-2 is what you want. Not 1—2---1—2-1-2jumpland1-2-1—2---1—2.
Couple of times you are landing dead losing what little impulsion came from the bid. You need to ride to the fence, over the fence and away from the fence with equal stride length, rhythm and pace. Need to keep looking up over and landing after too, when you look down, your upper body collapses and the horse sort of gets stuck trying to adjust balance to gallop away-also called landing in a heap.
Might help to shorten your stirrup and get off her back so she can carry and hold some pace. Looser elbow, more relaxed shoulder, hands out of your lap in a decent crest release, grab mane if it makes you more secure. Leave her alone, let her find her spots. And hit the flatwork, blowing thru halts is unacceptable and should not be allowed to continue, these are little fences, don’t be afraid to expect obedience and correct instead of let horse keep doing it.
Not sure a rubber snaffle is a great choice here. Not that she’s a wicked runaway or anything, she’s learned she doesn’t have to listen, so she blows you off, she’s learned she can, there’s nothing " honest" about that, she knows and she’s cheating.
Have to say she moves a little stabby besides short a few times. Overall does not look comfortable. That could be because you aren’t getting off her back or she’s just not a great mover with a great build for over fences work.