Why Did This Horse Dump a Woman Into a Water Trough?

Three sounds define this video.  The first is horse feed being poured into a bucket.  The second is a screaming woman that you HEAR and then SEE as she tries to stay on a galloping horse that's in a hurry to eat the food. 

The third sound is the splash of her being dumped into a water trough by the horse . . . who's really hungry.