Our riding school instructor was a retired mounted police officer.
We used to go train with the soldiers and rode like that.
Watch how they lean forward before dropping down, because so you can stay with the horse.
If you lean back as they do in the western movies, at speed you would end being slingshotted over the horse's head, plus the horse would have a much harder time balancing your weight over it's middle, not front end.
You do take a tumble easily if you let your horse get sideways, so you work very hard at keeping them straight down the slides.
We rode down some that were considerably more steep and long that those, where horses ended up sitting and sliding down at the end.
We never had a rider or horse hurt, but the soldiers once had one fall and break his arm.
As a teenager, those were wonderful "trail rides".