Video from a database:
Name of Video. Producer, Year Produced. Name of Database. Format. Day Month Year 
          accessed.
Example from Films on Demand:
Antigone. Films Media Group, 1984. Films On Demand. Web. 09 March 
                 2011.
Video segment from a database:
"Segment Name." Name of Video. Producer, Year Produced. Name of Database. Format. Day Month Year accessed.
Example from Films on Demand:
“Effects of Global Warming.” The Arctic Circle: On Thin Ice. Films Media Group, 
           2009. Films On Demand. Web. 16 March 2011.
Movies on DVD or VHS:
Title of Film. Name of Director. Names of Key Performers. Year of Original Film’s Release. Film Studio, Year of Release. Medium of Reception.
Example:
School of Rock. Dir. Richard Linklater. Perf. Jack Black, Joan Cusack, Mike White, and Sarah Silverman. 2003. Paramount, 2004. DVD.
YouTube video:
"Segment Name." Producer. Title of overall web site. Year Produced.  Format. Day 
                Month Year accessed.
Example:
“Japan quake: The force behind tsunamis. CNN. YouTube. 2011. Web. 16
            March 2011.
Here is a good place to place links to particular citation styles used in the subject area for your guide.
Some general examples:
American Psychological Association Official Website (APA)
The Chicago Manual of Style Online
The American Medical Association
From The Purdue Online Writing Lab (OWL):