I see an inexperienced dressage rider; I suspect she's a convert from hunt seat, and she doesn't have the tools in her toolbox yet to make the most of this mare. The mare looks to have a fair bit of schooling, since she leg yields from the quarter line without any fuss-not correctly, but she knows what those aids mean. Her simple changes also show experience, and I suspect she has single changes.
What I'd like to know is how long this owner has had her, since her topline is gone and neck muscles are upside down. (Did she ever have a neck?) She is broken at the 3rd vertebrae and BTV, showing that she's been asked to be in a frame before she has developed pushing power. That is unfortunate, but what I do like is that when the rider gets it right, she has moments of stretching honestly without curling. Her stride opened up considerably during the little stretching done in the first video, tracking up nicely, though got short again with lack of impulsion and riding corners in balance.
Her trot tracks up and she has great rhythm, with a softly swaying tail. I like her canter when it is forward and the tiny bit of walk under saddle showed overtrack. You can develop a trot, but you must buy a walk and a canter.
What do you know about her? Price?
The BTV thing can be fixed barring any physical issues, but it will take some dedicated work and a great eye on the ground. For the right price it may be worth the work!