That's awesome. I have seen it twice in person. Once while hunting at President's Island with two does and another time believe or not with two pretty good bucks during velvet in a bachelor group.
That's a common site in my backyard during the winter when the does are showing up in large groups. Get 15-18 deer in a small food plot together, and they really go at it.
I've got a video of 2 deer doing this, and one of them fell over and almost took out the camera.