Dinosaur Jr.‘s video for “Over It,” from the group’s latest release, Farm, is just about perfect: Three old rock geezers biking and skateboarding around town and grinding rails. Most of the tricks are done by stand-ins, of course, but it’s an apt metaphor for the role the group has embraced as elder statesmen of indie rock. If kids start worshipping guitarist J Mascis instead of Avenged Sevenfold, for example, Hot Topic might well go out of business by 2011. And if they get hip to the music of bassist Lou Barlow (of Sebadoh fame), the phrase “emo” may well regain a positive connotation. Mascis and Barlow — the two stoned leaders of a brighter tomorrow — team up Monday, with Barlow setting the stage with cuts from his latest Merge Records release, Goodnight Unknown.