http://www.incubusthefilm.com/
"
Starring William Shatner, Allyson Ames, Milos Milos (as "The Incubus"), Eloise Hardt, Robert Fortier, and Ann Atmar, Incubus was
the first American movie to use the artificial language Esperanto. You will hear a young William Shatner speak it in this 1965 film, a few years before he found fame as Star Trek's Captain Kirk."
(emphasis added)
r!