WordNet (r) 3.0 (2006):

sneak preview
    n 1: a preview to test audience reactions

Moby Thesaurus II by Grady Ward, 1.0:

43 Moby Thesaurus words for "sneak preview":
   3-D, Cinemascope, Cinerama, Technicolor, Western, animated cartoon,
   black-and-white film, cartoon, chiller, cinema, color film,
   creepie, documentary, documentary film, educational film, feature,
   film, flick, flicker, horror picture, horse opera, motion picture,
   motion-picture show, movie, moving picture, newsreel, nudie,
   photodrama, photoplay, picture, picture show, pornographic film,
   preview, short, silent, silent film, skin flick, spaghetti Western,
   talkie, talking picture, thriller, trailer, underground film