Board Thread:Metal Gear Solid V/@comment-207.118.85.188-20140929210238/@comment-25090680-20140929215702

Found this on the wiki don't know if it helps, seeing as how apparently i didn't do the mission right and get the real tape. Or if this is even the tape you mean (haven't played in a few months.)

"On December 21, 1974, at 18:08, Big Boss, the leader of MSF, personally infiltrated the base by stowing away on the back of a truck, noting the presence of several armed guards before locating the agent. However, because of the security being heightened to the extent that casual conversation would have risked blowing the agent's cover, Big Boss instead placed the agent in a chokehold and "interrogated" him so the latter could relay the tape or at least its location without drawing suspicion. The agent admitted that he doesn't have the tape on him, and tells him it was at the central control tower at the admin building. He also attempted to warn Big Boss about XOF and Skull Face, but decided against it before telling Big Boss to put him in a sleeper-hold to ensure his cover remained intact. Big Boss deduced the tape, that was obtained in the control tower, was in fact a trap after seeing a surveillance camera at the location. Big Boss then returned over to the agent and interrogated him again. The agent revealed that his cover had been blown and that they had held his family hostage, forcing him to set them up. He then informed Big Boss that a Marine with a shaved head had the real tape. Big Boss then located the Marine and proceeded to force him into giving up the tape, although the Marine nonetheless was confident that MSF could not stop their plan even with the evidence. Big Boss then proceeded to escape."

Source page