Ninjaboi created a documentary called "From Street Corner to Webcam: The History of the Underground Mainstream of Hip Hop Dance". It covers the history of the dance form, how it has evolved, its portrayal on TV and in movies, the pull between art and commerce, the future, and other topics. It's long (48 minutes) but really worth watching for its great clips, thoughtful analysis, and Ninjaboi's dancing at the end of the film. He's even prepared FAQs about it -- click here to access them.
From Street Corner to Webcam: The History of the Underground Mainstream of Hip Hop Dance from Ninjaboi B on Vimeo.