Unless you can find a way to weave cryptography into light, it will always be possible to trick a video camera into recording something that is "fake". Trust is what society is built upon, we're not going to get away from it now.
Then, when a questionable event happens, the video of all participants and anyone nearby can be replayed. Then, all videos of participants can be replayed to make sure they match up, and the video of the time leading up to the event could be scrutinized. Furthermore any one who visited that area in the recent past could be checked to make sure they didn't create some sort of hologram or something that the participants watched rather than the real thing.