Silk White didn’t go to film school, doesn’t have an agent, and hadn’t set foot in Los Angeles until May. But the former drug dealer turned independent filmmaker generates nearly $2 million annually from his movies and television series. White works in a nascent middle ground in the show business economy, between YouTube creators chasing algorithms and professionals backed by studios. Most of his earnings come from free streaming services like Tubi and the Roku Channel that share advertising revenue with him. White is emblematic of a generation of producers building careers on those platforms with content they finance and…