I watched the end of the video more closely and have this to add–
At the end when she is being snaky, in addition to flinging the rope at her, you also grab the halter and punish her in the face. And, while you are even with her head, you are trying to get her to go forward. Move away from the horse towards what you want to be the inside of your circle with your head down (drop your chin but keep your eyes aware) and shoulder to the horse (so you can still see her if she follows). Keep trying to move towards a place that is center of the circle but behind her shoulder level. When you have good distance between you and her (being mindful not to have a bunch of slack in the line), start moving towards her butt with your whip pointed towards her butt, sort of parallel to the ground. If she continues to swing to face you, continue to walk to follow her butt until she begins to walk on. Then, being in your non-threatening position, you can push her out to a bigger circle and let the line go some as she moves out.
In your video, you either move further in front of her, or you are holding her face (which we already see is threatening to her) while pointing the whip at her flanks. So, even if she did move, where would she go but to continue to spin and face you? Her reaction is also to go backwards and face you, so yanking on her face is the wrong correction–this would maybe be ok to try to get her attention if she was dragging you off into the sunset. Putting your hand up by her face to grab the halter after she already threatened to bite you seems like you are asking for it!
You can work on this stuff on the ground with no whip and just a longer lead rope to learn the difference between threatening in her face body language and kind body language that makes mare want to follow you around.
As I said earlier, it may be best for a competent trainer to show you this in person. And, I agree with the poster who said to try it out on one that’s easy to longe first.