There is a common misconception of permissible uses of copyrighted videos on campus that I thought should be mentioned. On a fairly regular basis a student group or academic department asks for permission to use a library copy of a feature film for an open screening, believing they are permitted to without acquiring public performance rights because it would be used in an educational setting. The truth is that the feature films in our collection, roughly 25% of our holdings, cannot be used for those screenings because they are sold with what are referred to as "home-use" rights. The reason "home-use" titles can be used in classes is that there is a face-to-face teaching exemption in the copyright law that allows it. There is a clear distinction however between the classroom and, say, an event where faculty or students are present and have a serious, scholarly discussion before or after the film. The latter scenario is not covered by the exemption. There are several requirements that must be met to qualify for the exemption but the one that seems to be least understood is that the performance must be incorporated in systematic instruction. Systematic instruction means, more or less, a formal class for which one would register.
Feature films are almost never sold with what is called "public performance rights", though many documentaries are, so if a campus group would like to hold an open screening of a feature film, and by that term I'm referring to what one might also call a "movie", it's necessary to either get permission from the copyright owner or pay for "public performance" rights for the particular screening, typically through a commercial distributor. The cost difference between the purchase of a home-use videotape and a one-time public performance license is usually substantial, along the lines of $20 vs. $200-$1000+. By the way, if a film is a documentary, one shouldn't assume we have public-performance rights for it. Many documentaries in the Media Services collection have only home-use rights (e.g. Fahrenheit 9/11, Control Room, March of the Penguins).
Distributors that commonly sell their documentaries with public-performance rights include PBS, Bullfrog, Cinema Guild, Filmakers Library, Films for the Humanities and Sciences, First Run Icarus, and Women Make Movies.
Here's a useful guide on the subject with a full explanation of the requirements of the face-to-face teaching exemption, from College of St. Benedict, St. John's University: Facts about video programming on campus.