This reminds me a great deal of the Spanish Dancing horses (the one's crosstied and whipped into 'dancing', not the well bred and cared for gaited horses). I'm not saying it's the same, but I believe this horse was trained with some very similar methods... Not good at all.
One of our rescue horses was a Spanish Dancing horse and she clearly suffers from some serious PTSD. She goes 'blank' where her eyes go empty and her whole body goes quiet and she kind of trembles softly, then all of a sudden she'll go wild-eyed and lunge out and bite the wall, trotting in place and kicking out with her hinds, like little pops off the ground. At the sight of a whip she starts jogging in place, she couldn't be lead or sat on without trotting, at whatever speed you expected, but always trotting. It was like she didn't even know she could walk on lead or undersaddle. She's getting better now, but I truly fear for horses like her. I don't think they could ever really function well in life outside of circus/parade acts like this - and the life they're living IMO is as terrible as it gets.