It's Wed again. Let's write another couple of cinematic words.
Closed set
A set, either in the studio or on location, that is not open to any visitors, including studio executives, and is open only to the director, performers and crew. Sets are closed if a particularly intimate or controversial scene is being photographed, if the subject or treatment is to be kept secret, or if there are problems in the production itself that must be worked out.
Stunt
An individual who substitutes for an actor or actress to perform some difficult or dangerous action. This person must of course, have some resemblance to the original performer and be dressed in an identical manner. Shots of such action are taken so that the identity of the stunt person is hidden. Stunts are specially adept at taking falls, surviving crashes or playing piano. When a film requieres a group of such people performing a number of these action, a stunt coordinator is hired.