His friends were just always in a paranoid state because of the D...so they really did not know the cameras were there. The note on the door was silly. He said he left the note on the door saying come in as a trap because he didn't feel anyone WOULD actually come in and then when they saw someone DID come in they were all paranoid. I kinda thought that part was funny.

He didn't watch himself on the monitors. He watched them but there was another cop in one of those suits that watched them all.

They were actually seeing if they could trust him enough to get him to spy on the company that got people off of D which was really the company that was making it. Does any of this make sense? I am probably not explaining it very well.