No true movie junkie is going to want to miss Side by Side. In case you haven’t noticed, digital capture and projection are slowly sending old-fashioned celluloid into the archives. What does it mean for movies? Keanu Reeves, making an astute and witty interviewer in Chris Kenneally’s vital film, asks many of our best directors where they stand in the digital revolution. Their answers might surprise you. Steven Soderbergh and David Lynch are eager converts, while Christopher Nolan and Martin Scorsese feel a loss. The film clips, side by side, are revelatory. Jump in.