Alright, what the hell is brachiation? Basically it's to move about by swinging from hand to hand. This is a very rare mode of locomotion on this planet, apes being about the only family of animals capable of true brachiation. But guess what! We are capable of this amazing feat too because we're apes! Now, there is reason to believe that in our evolutionary past we gave up some of our brachiating prowess in order to run around better (long legs), and throw stuff better (wider shoulder girdle, shorter forearms, more stable wrists), but the ability remains, so lets put it to good use. Besides, there are some people (myself included) that believe you can't have truly healthy shoulders without doing some brachiating now and then (I think I heard Kelly Starret PT talk about this once on CrossFit Radio). After all it's what our shoulders were originally designed for.
The first video is of a couple of white-cheeked gibbons showing the extreme of what is possible for brachiators. The second shows a bit of what is possible for us humans. We might not be able to swing around quite as well, but check out what our long, and strong, legs make possible.