If you look at the very beginning of Max's video, he does 4 in a row — in his case, he does a half turn in the hop and then finishes the full turn on his hands before repeating. The first one is quite straight-line, but the ones after turn a bit more than half + half, causing the circular motion.
I would think that on the horse, Max will have to do it just like at the beginning of his video — half turn hop + half pirouette on the leather. If he came back the other way that would be CRAZY hard.
BTW, there are all kinds of variations that breakers do, such as doing it on the elbows are spinning more in the air before catching. Ignore the bent legs and flexed feet — breakers care less about good form, and actually flexed feet probably is considered cool by most of them.