Lots of good information for you here.
I watched your other videos and wonder what much more experienced COTH’ers than me would say. The jumping video? Your mare sticks her nose out and just kind of zig-zags around. She doesn’t go forward in a straight line, and her face is somewhat not connected to her body. Maybe more time on basics before jumping would help pull the package together.
You ride her quietly, she just seems like a bit of a ‘loose horse’ underneath you, as the saying goes.
The comments from others on her dropping her leads behind and so forth are interesting. When jumping she does the same thing, so she’s either so out of condition for the work that she can’t hold things together, or something hurts.
I spent extra time on watching your videos because your mare looks SO like one I had with the same problems. She was a gorgeous buckskin half-Arabian, half Quarter mare with a mane about two feet long… just a beautiful, beautiful horse, and kind too.
But she was always dropping her hind lead, cross cantering… if I really held her together under saddle she could hold the lead, but on the longe she just would swap back and forth like a car with a bad wheel. Not lame, just… wonky.
Finally, after a successful and capable trainer had her for a little while and said "something’s wrong’ we did the work to find out she’d fractured her pelvis (MRI finally) at some point in the past and had major healing/alignment trouble and she was not going to get better.
I just trail rode her for awhile (which was OK) but when she started having intermittent issues in front, I gave her away to be a pasture pet.
Even watched your video to see your mare’s face, wondering if my horse had made it into your video!
Good luck, you’re trying hard to be a good horse parent! If you can find the right kind of help in your area, you’ll probably get a lot more enjoyment for your effort.