 They just started releasing some of the songs like You've Lost That Lovin' Feelin'. Sonny and Cher had released I Got You Babe about a month earlier, which was their big breakout hit. The Byrds already had number ones with Mr. Tambourine Man, and now, of course, doing the Pete Seeger item of Turn, Turn, Turn in 1965. And, yes, the headliner was the Beach Boys. They say they finished the show with this song.