I really dislike videos done in this manner. Instead of as solid section of video so we can really see what is going on, its all broken up with melodramatic writing. There is no piece in this video that is a long enough uninterrupted action shot so we can really see what is going on.
From what I can see there is nothing horribly wrong. I rewatched the video full-screen and majority of the time the whip is behind her which is considered a neutral position. The couple times I saw her use it, it looked to reinforce a cue the horse blatantly ignored and it looked like she aimed for the chest/high in the leg area. Not necessarily the way I would go about training, but nothing I would freak out over either.