The punch comes at :33 in the video. Watch the man with the blue coat and the red beanie. All of a sudden you'll see his arm come sideways and the horse's head jerk backwards:
At the beginning of the video you can see other protesters either yelling at the officers or yelling at the horses. Protesters then rush at the officers, but pretend that they're not doing anything wrong by putting their hands in the air like imbeciles. At :26 you can see one such moron take a Pau Gasol-esque flop.
|That's right, genius. Rush into a crowd of officers and then raise your hands|
But, you know, they're so peaceful.