Matt Steffanina, an online celebrity dance coach, has just uploaded a rallying cry to his doting 13.8 million YouTube subscribers, admitting that creating dance videos for YouTube—after 17 years—is just not cutting the mustard anymore. “I want to do documentaries, I want a Netflix series,” Steffanina implores in a rags-to-riches video which is ultimately intended to direct dance enthusiasts to his dedicated dncr.com subscription site, far from YouTube’s clutches. This is the latest instance of successful YouTubers decamping – spending less time uploading content to the platform that made them famous, and injecting more effort into platforms that can make them money, serious money. Steffanina estimates that record labels have siphoned off $15 million in revenue from his content. “You’re…