He looks like a sweet little guy and seems really gentle and broke, but there's no way I'd pay that kind of money for a horse with such wonky conformation.
As others have said, he's got a super long back, massive sickle hocks, an all around weak hind end, and either his front feet are mildly clubbed or he's got a terrible farrier who's making him clubby. Upright shoulder, fine bones, weak knees. He also appears to have a very slight gimp on that right front, the one that's clubbed a bit more. I wonder if they've got him padded up like that as a treatment for navicular changes...
He might also toe out badly on the front and might be knock kneed. You can get a good idea what his fronts look like in the video at 3:20 when he's coming straight at the camera.
Also, he's a very unimpressive mover. His trot is okay, but his lope is terrible. Short, choppy, heavy, no cadence at all.
I suppose if I was looking for a decent starter horse for a young or beginner rider, I might look at him because he seems safe, but my first stop would be with an extremely thorough PPE and dropping the price to about $1500.