From Sondheim's heyday in the 1970s - a David Frost interview with some of the cast and crew of Follies.
In particular, Sondheim talks, along with director Harold Prince and librettist James Goldman, about the origins of the musical at 36:35, and at the 1:00:00 mark, there is a performance by the quartet of young people singing "You're Gonna Love Tomorrow/Love Will See us Through" - a good example of Sondheim writing charming music and cleverly-rhymed, as well as apt, lyrics.