Lian Lunson’s torturously dull 2005 documentary, which seems like an extended DVD bonus for a yet-to-be-made biography, shows the Canadian singer performing only once, with U2. Mostly it’s a tribute concert, with his repertoire performed by other singers, including Nick Cave, Rufus Wainwright, Kate and Anna McGarrigle, Martha Wainwright, Beth Orton, Linda and Teddy Thompsonall of whom, like Cohen, are typically filmed in close-ups so extreme that we can’t even see their chins or foreheads. And we learn almost nothing about Cohen’s life, apart from the fact that he comes from Montreal and once trained as a Zen monk. PG-13, 105 min. (JR)