You can show your personal DVD to as many people as you like, and the filmmakers encourage you to do so. However, in an institutional setting such as a high school or university, a different set of rules applies. Showing the film in these settings requires additional rights.
The Corporation is available on DVD and VHS for educational use. There's a 3-part VHS tape, or a DVD that comes with 5 short thematic modules teachers may find useful, as well as password access to a study guide. Before contacting us or our distributor about holding a screening, please check with your school's library or media department to find out if they've already bought a copy of the film.
When an institution buys the educational version, that DVD comes with public performance rights, that is, the right for that copy to be shown to groups of students, over and over, till the messages of the film sink in and the world is saved.
Note: You or your school needs to purchase this version if you are planning to use it for classroom or other public performance uses. The home DVD is not licensed for these uses.
See here for information on the home edition.