Lou Reed’s latest performance video looks and sounds like a wake, which is precisely the point. Magic and Loss, his most recent album, is an alternately bitter and thoughtful song cycle about the deaths of two close friends, and this performance of the album, filmed on a soundstage with no audience to distract from the occasion, is appropriately somber. (Even a concluding run-through of Reed standards, including ”Sweet Jane” and ”Walk on the Wild Side,” is pretty grim.) The album is important in that it shows rock’s master of deadpan willing to be more up-front with his emotions. As a stage piece, though, it doesn’t always make for riveting viewing. Reed (in professorial Ben Franklin glasses) and his band work their way through songs like the angry-at-death ”Warrior King” or the resigned ”Dreamin”’ solemnly and intently, and the fuzzy camera work, which reduces the musicians to spectral blues and reds, doesn’t help. Yet when Reed lets out a rare smile during a blast of feedback raunch toward the end of Magic and Loss: Live in Concert, it’s conclusive proof that in times of grief, music can truly be therapeutic.