★★★ out of four stars When: 7 & 9 p.m. Mon.-Tue. Theater: Trylon Microcinema.

A trim, informative 99-minute primer on celluloid film, which to many viewers has a warmth and feel as soothing as buttered popcorn, and the brave new world of digital cinema. With Keanu Reeves as on-camera interviewer, writer/director Chris Kenneally assembles a gallery of stunning screen images and recruits a stupendous roster of filmmaking talent to weigh in. The lineup ranges from digital advocates Martin Scorsese ("we're on another level") and James Cameron (extolling "possibilities you couldn't do on film") to skeptics like cinematographer Geoff Boyle (who asks unanswered preservation questions and predicts "in 100 years there won't be a trace of this left"). For any movie buff pondering the promise and challenges of cinema's new cyber era, or the way filmmakers visually sculpt images, paint pictures and tell stories, this is a must-see. (Unrated.) COLIN COVERT