You know this person Tuffy?
Heh... I've had it happen jumping, all momentum headed forward, and they hit the brakes at the last minute :~D
Could be sour, you're right... could be that the horse has begun resenting the final run.
I have a minute to respond, my little girl is still throwing up. She got a bad case of it, I'll tell ya.
No, I don't know that person. I just ran across that video when I was surfing.
One thing that I noticed in that video is the girl is trying to make herself look like a better rider than what she is. Even professional barrel racers hang on to the saddle horn, so as not to jostle the horse going around the barrels, or even worse, get left behind. That horse might not like the way she's bouncing around in the saddle going around the barrels. An old experience horse probably wouldn't care, a young, inexperienced horse, probably would.