Previously known as Dance Heritage Coalition's Dance Preservation and Digitization Project, this collection now resides at USC. It "preserves culturally significant recordings that document global and U.S. dance traditions, creative work by outstanding choreographers and performers, and performances that helped to advance the art form." Content continues to be added, but not all content is publicly available.
Video content from the trust that "preserves and maintain the integrity of the choreographic and other works of Merce Cunningham and Cunningham Technique."
Videos from the Trisha Brown Dance Company, which is "a post-modern dance company dedicated to the performance & preservation of the work of Founding Artistic Director & Choreographer, Trisha Brown."
Newsreel and documentary films stretching back to the early 1900's, including some coverage of dance. Example search terms: dance, dancer, ballet, choreography, swing, ballroom.
This series of videos from Steezy defines dance terminology and then demonstrates the terms with video clips of various artists performing the technique.