She looks to be round about 16 hands. We had a Callaway horse at the showbarn I used to work at. He was 5 gaited also, but he had problems with his hocks swelling up. We kept them wrapped unless we were working him or he was being ridden.
I don't know if I'm seeing it right in the videos, but is she cantering on the right lead? Also, if you're going to be taking her to any of the bigger shows, you might want to get your trainer to work on getting her front end up a little more. We had a buckskin horse whose knees would almost come up to her chin.