Avoiding Luke Skywalker's wrath, could it not be believed that the Jedi would record their interaction with Palpatine when they went to arrest him. Getting the camera in there would be a problem, but then again, they were the keepers of the peace or basically in charge of security, thus would have control of survellience video.

Even if Palpatine was overtly evil, the Jedi would have to watch the tapes in his office at all times to catch anything that might give it away. I just don't see them doing that. Also, I'm sure it wasn't intended but when Palp reveals himself to Anakin, they walk out of the office into the hallway area. Could that be to avoid detection. I'm sure it wasn't intended.

But then again, the video doesn't play exactly the same way the scene does in the movie, does it? I remember seeing it and think, that's not what he said!