Films, Screenplays, Etc.
The titles of works in visual media are normally given using either italics or underlining: Bewitched, Vertigo, etc. (Same goes for the titles of paintings.)
Material quoted (either from viewing or from reading a published script) may be treated like dialogue in fiction: As Samantha says at the end of the scene, "_______."
If an extended exchange is quoted you may treat it like lines of dialogue from a play, indicating all the speakers.
If a printed script is used, cite it as you would any other text, with page numbers and a full citation in the Works Cited.