The Camera is found in the Armoury South, close to where you fought (SPOILER)Revolver Ocelot.

From the boss' room, head out through the hole you made to get inside. From here, head right until you reach the end of the corridor. If you examine the wall you'll notice that it can be damaged by C4, so blow a hole through it. There are gun cameras in this room, so either evade them or use a Chaff Grenade. You'll see two doorways, which require a Level 4 (?) keycard to enter. The Camera is inside one of these (the southernmost one, I believe).

Hope that helps.