Stephen Sondheim‘s 1964 musical Anyone Can Whistle [Wikipedia] was a genuine flop. It’s rarely produced, and the original production was never filmed. But in 1995, a concert version was mounted at Carnegie Hall as an AIDS fundraiser, starring Bernadette Peters, Madeline Kahn, and Scott Bakula. Presented in glorious single-camera VHSovision, that performance is on YouTube. [2h9m] Here is a half-hour lecture on the background of the show. [Vimeo] Here is the Broadway libretto [PDF] if you want to follow along.
The Broadway production included extended dance sequences, was presented in three acts, and is a social commentary about politics, manipulation, and the nature of sanity.
You might also enjoy this single camera audience bootleg of the 2010 Encores! concert performance at New York City Center [2h31m]. It’s a bit more of a performance than a readers’ theater, and includes Donna Murphy, Sutton Foster, and Raul Esparza.