The Art of Love
This 1920's film is probably the first of the ever popular sexual positions films.
This instructional film depicts sexual positions both men and women can enjoy. As the film begins, we see a man and woman enter a bedroom (both of whom are nude). Various text screens explain the sexual activities. Between text explanations, the couple illustrates a variety of of sexual acts. The film ends with the couple cleaning themselves using a towel and exiting the room.
Stag film definition: http://www.sexsmartfilms.com/articles/stag-films