Earlier this week, you saw Dave Grohl performing live on stage at HBO’s Concert for Valor. Tonight, he performs again – a new song, inspired by the things he heard and saw while tracing the history of modern music in Los Angeles. Stops along the way include The Doors, NWA, Joan Jett and the Runaways and The Eagles, so this installment of Grohl’s very personal music appreciation course is wide-ranging indeed.