I'm a bit confused as to what the rider was trying to do with the calf. Seemed like he was just chasing it around so finally the calf got fed up -- it felt cornered. ANY animal will go on the offensive when cornered. And that calf definitely only saw the first horse as the threat; when the 2nd rider came in the calf was not very offensive to him.
I would have been inclined to give the calf a good boot in the nose with my foot. Rules or not.
Maybe I'm missing something...I'm not seeing any horns on those steers. Yes, it would suck immensely if those calves had horns, but they don't...so why can't you just appreciate the humor of this particular vid?