Here is the official statement and wording:
http://www.copyright.gov/1201/2010/Librarian-of-Congress-1201-Statement.html
(1) Motion pictures on DVDs that are lawfully made and acquired and that are protected by the Content Scrambling System when circumvention is accomplished solely in order to accomplish the incorporation of short portions of motion pictures into new works for the purpose of criticism or comment, and where the person engaging in circumvention believes and has reasonable grounds for believing that circumvention is necessary to fulfill the purpose of the use in the following instances:
(i) Educational uses by college and university professors and by college and university film and media studies students;
(ii) Documentary filmmaking;
(iii) Noncommercial videos