I actually found it quiet humorous! Lol and i've hit my horse harder then that giving her a pat for being good. I bet they are actually good riders who got bored running around in the arena and jumping so they decided to have some fun! Honestly looks like something I might do. And what well behaved horses = )
I actually had a really good chuckles over it. I think the idea WAS to mock people who DO say ridiculous things about it being a stupid horse or hit their horse for doing something that was their fault.
I'm not sure she even touched the horse with her fist, it looked like she was just hitting "air" to make it look like she was beating it.
I'd rather see kids having fun and being goofy and loving on their horses then taking everything so seriously and making their horses unhappy.