I can't see the video in link. Is it this one?
I have to say it was funny. And in most cases it was NOT a horse's fault/training from what I see but rather the rider sitting like a sack of potato (the girl sitting the bronco horse did a great job holding on BTW).
I did go to the local barrel runs several times (just to watch), and I was quite appalled to see some people who barely can ride try to run barrels. In fact I know some of those people in person. With that being said there are also really nice horses and solid riders out there. So like in any discipline: there are good riders and good horses, wacko riders and good horses, and wacko riders and wacko horses. :)
BTW, I do agree the original post sounds like bashing to me.