My money is on some promotional scheme for the new planet of the apes movie coming out.
Reasons:
* Chimp/ape not freaked out by gun firing
* If said chimp/ape was not freaked out by the gunfire, why the chimp/ape stop firing so soon?
* gmoon has stated other reasons this doesn't seem real, and I'd have to agree.
-- the gunfire doesn't overload the camera's audio.
-- the chimp raises the gun over his head after "pwning" the soldiers; all very youtube.
-- the camera framing/movement looks very professional to me. Carefully planned and directed "amateur footage."
More than that seems bogus...that's just what hit me initially.
It's a marketing thing for the new planet of the apes movie.
http://www.youtube.com/user/apeswillrise