I have several barrel racing (and gaming in general!) pet peeves. Most have been mentioned but heres one I just don't get. People whos horses are gate or chute sour. Its common in 4-H to have to be walked in by someone brave enough to hold your horse down. Once they get in the ring, the horse is on its hind legs pawing at the air. If this is happening...you are doing something wrong. A horse should love its job. A good gaming horse walks in (like all the girls in the videos demonstrated) runs a nice, fast, tight pattern. Stops when asked and walks out. The girls at open shows and local rodeo pumping their horses up before a run are, in my opinion, idiots. Your wasting the energy!
A good gaming horse shouldnt need any more than maaaaybe a bumper spur for a clear cut leg signal. I see way to many girls with giganto spurs digging them in. Jeez...I wonder why he bucks on the run home?
All this beating has to stop. A tap with an over under for encouragement is not what im talking about. I saw a girl last weekend almost fall off her horse smacking it so hard with an over-under. Same show, I saw a little girl on a tiny little pony who was trying his heart out. She had a leather bat and was sitting STRAIGHT UP on the run home, just so she could beat his butt the whole run. Then was mad that he didn't do well.
As far as the OP goes, I think what you might be seeing is a powerful horse rocking a rider upright. My horse has a huuuuge hind end and when he comes out of a turn, his thrust pops me upright and sometimes back. By the time I correct myself, its time to turn again! LOL Upper level riders have this master...I play with games but never take it seriously.
Oh and to the two girls in the videos, nice job. In my area, you see alot of 'pull and jab' riders...both of you ride a pattern well and have horses that can excel. Good luck!