Last week I saw a terrific documentary called “Girls Rock!” about musical chicks aged 8-18. Tonight I saw “Young @Heart,” a profile of a rock-inflected chorus whose average age is 83. The movie opens here Friday, when I’ll have a review.  In the meantime, here is the most bizarre scene of the movie, in which the old-timers sing the Ramones’ “I Wanna Be Sedated” with varying degrees of self-awareness: