Screen Grabs: RSVP to William Greaves’ elbow-throwing Harlem Renaissance after-party

William Greaves was a prolific documentarian for several decades, but since he passed away 12 years ago at age 87, he’s become best-known for works that were seen barely or not at all during his lifetime. The experimental feature Symbiopsychotaxiplasm: Take One was shot in 1968, blurring lines between fiction and nonfiction as it depicted a director (played by himself) losing control of a project filmed in Central Park. At the time, no one knew what to make of this quasi-verite, semi-improvised, relentlessly self-questioning objet d’art. So it basically vanished—until much later, it attracted fans including Steve Buscemi and Steven Soderbergh, who not only secured a belated release but helped Greaves secure means for a 2005 “sequel” called Symbiopsychotaxiplasm: Take 2 1/2.  Still, those were avant-garde endeavors destined for limited audiences. Now, however, the late Greaves has a “new” movie likely to be seen by more people than anything since the days when his portraits of Africa