Last weekend, we learned a few more vague details about the National’s forthcoming Grateful Dead tribute album — it will likely feature members of Bon Iver, Vampire Weekend, the Walkmen, the War on Drugs, and Kurt Vile & the Violators. On a very related note, yesterday at Outside Lands, Bob Weir (of the Grateful Dead) actually joined to National onstage to play “Terrible Love” from High Violet. (The band previously played with Weir at the Bridge Session lasat year.) Watch the performance below.