It is an antelope and has horns not antlers. Somewhat unlikely it is all that much like a deer, since our rut is built around winter. But yeah, could be rut behaviour. Looks like he nailed the guy. Even though he could have killed him, that doesn't mean every time they whack something, they want to kill it.

Look at Bambis footwork in this case. Kinda simmilar use of the feet on impact. Latter half...

http://www.youtube.com/watch?v=l0DkEcZ_k8Q