I regret not being able to understand the language. The horse is very resistant for part of this ride. For all I know, he's describing that resistance. I don't think you can fairly judge the way he is moving based on this video. His tail is wringing; his mouth is open and his head and neck are in an awkward position. In other breeds, we get this kind of resistance when youngsters are asked for too much too soon. I have also had short periods of this "stuff" in a training session just before everythig got wonderful, but I wouldn't have filmed it for public consumption.
Nancy