Gather your information. This includes full title of the DVD, year and country of original release, director, film studio and any other relevant information.
Parenthetical or in-text citations should be written as (Title, Year). If you use the name of the DVD in the text of a sentence, the citation should only include the year. For example:
While telling the origin of the friendship between the mutants, the movie (X-Men 3, 2011) fails to create.......
OR
X-Men 3 (2011), while telling the origin of the friendship between.....
Of course there is always room for interpretation in Harvard style, and Staffordshire University suggests parenthetical citations should be (Director. Year):
X-Men 3 (Ratner. 2011), while telling the origin of the friendship between.....
There are different schools of thought on how to create the reference. For example, Anglia Ruskin University suggests a reference like this:
Full title of DVD-Italicized. Year of Release. [DVD] Director. Country of Origin: Film Studio. (Other details - narrator, etc.).
Staffordshire University uses Harvard style to reference a DVD this way:
Director's Last Name, First initial. (Year of Release). Full title of DVD-Italicized or Underlined. [DVD]. Country of Origin: Film Studio