Mythbusters investigate hypnosis and it's effect on recalling past events. The experiment included having three witnesses to an event, asking those witnesses to recall some specific details about that event, then hypnotizing them to see if they could recall better.
I must admit that I always suspected hypnosis was fake, but I now figure if it was then these "scientists" would have just stood there and stared at the people performing it.
For the first part of the episode: http://www.videosift.com/video/Mythbusters-Post-Hypnotic-Suggestion-rfte
PS: I know the quality is sub-optimal, working on a better one now.