Hidden cameras are also sometimes used in reality television to catch participants in unusual or absurd situations. Participants will either know they will be filmed, but not always exactly when or where, or do not know they have been filmed until later, at which point they may sign a release of give consent to the footage being produced for a show. This latter sub-genre of unwitting participants began in the 1940s with Allen Funt's Candid Microphone theatrical short films . In 1996 the genre was given an overhaul by Travis Draft who introduced the glasses cam with his show Buzzkill. The show took hidden camera to a whole new level where the performer (Draft Himself and Cronies) were the focal point.
credit : http://en.wikipedia.org/wiki/Hidden_camera#Hidden_camera_shows

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