OntheBoards.tv * has cutting edge, contemporary dance videos. Completely unique content.
ArtFilms Digital: Dance * primarily provides contemporary dance films, with a focus on dance from Asia, Pacific Islands, and Australia.
Dance in Video (Alexander Street) * has over 1000 hours of video. The majority is classical ballet, interviews with professionals, with a heaping helping of some (classic) modern and jazz.
Ethnographic Video Online * is intended to be a visual encyclopedia of human behavior. Includes videos of dance. Searchable by keyword, geographic location, cultural group, and subject of the video.
Numeridanse.tv has over 1700 freely available, high quality dance videos. Many are European focused. Some documentaries and educational resources available as well.
Jacob's Pillow Dance Interactive is the online archive of many of the performances performed at Jacob's Pillow throughout its history. Includes performances by many monumental dancers and companies of the 20th century from all genres of dance.
New York Public Library Digital Collections has recently begun to digitize and make many of their unique dance films available online previously only available by visiting the Jerome Robbins Dance Division reading room. Alert - some videos may only be viewed from computers in NYPL. These are indicated with a lock symbol. They can be excluded from your results by toggling the "Exclude Location-Restricted Videos" button.
Dance-Tech TV offers unique videos focused on the intersection of dance and technology, both performances and talks.
Dance Channel TV provides a couple hundred unique and high quality dance videos. Offerings focus on ballet, a Meet the Artist series, and dance documentaries.
UCI Libraries holds thousands of DVDs (and even some VHS!), many of which are related to dance and other performing arts. Most all DVDs can be checked out by any UCI student or faculty. You can find them with UC Library Search.
After you've searched, look at the left side of the screen and use the Resource Type limiter to narrow your search to videos (see image below). This will bring up both online streaming videos and physical videos in the Libraries' Multimedia Resources Center.