THAT IS DESPICABLE.
Keep in mind though that those clips are from one training stable. You can't condemn all for the actions of one.
I am SOOOO GLAD that you posted this and SOOO GLAD that somebody took the trouble to take these photos. You can see the pain in their bugged out eyes. I never saw this look in my (natural) TWH's or TWH mixes. BUT, we did have experiences with "Merry Boy's Hart" that indicated past abuse, like when he tripped with my DH aboard. He took a fall--no injuries bc he rolled off, really, but the HORSE took off as if we were going to beat him. I think we finally convinced the horse that we didn't treat our animals like this.