featurette

A featurette is a term often used before the 1970s to refer to a 20 to 45 minute film (longer than a short subject but shorter than a feature film), usually a "making of" or "behind the scenes" mini-documentary, or an extended trailer, which was usually displayed by theater owners to "sell" a film for exhibition in their movie house. Today, featurettes are commonly run on premium cable stations or offered as a "bonus feature" as part of a DVD's extras. See also "Making of..."