CIA Threatens 9/11 Researchers After Discovery Of Cover Up

I only watched about half of the video thus far, and I although I am not surprised that the CIA would withhold such information, my main question is "why?" Could it be true that plans were already in the works, from the top level of the CIA, although very compartmentalized, to stage the events of 9/11? I mean what other reason would the CIA have for not wanting to out known terrorists in the US? Terrorists who later were involved in 9/11?

Well I can understand not wanting to "out" them by arresting or deporting them, but to not share this information with one of the people who most needs to know, stinks of a coverup to me. They apparently did not want anyone else, including the FBI, to know these terrorists were in the US, because they did not want anyone to interfere with the plans that certain CIA officials and politicians had going with these terrorists.