The cameras in the office are fake, but the reach of Kuwabara's paranoia was limited, and the cameras outside work as cameras should—with real parts, and images fed away. One of them points directly at the door, and that's luck more than anything else.
Naoto gets a copy of the video.
He gets it easy, is the thing. He doesn't have to bargain for it, and the fact he knew Kuwabara—shouldn't be there, in other words—goes cheerily ignored by everyone with a badge.
It's either money or fame...or maybe something else. Yousuke keeps his mouth shut.