This may be my favorite of those I've seen. It is the "first draft" of the song "Blown' in the Wind" as performed by Peter, Paul and Mary. (Though written of course by Bob Dylan.) And the group here is portrayed by Jimmy Fallon, Kevin Bacon and Kyra Sedgwick. Fallon, of course, is known for singing and playing the guitar in numerous sketches, and Bacon was part of an actual musical group, the Bacon Brothers. But it's a pleasant surprise to see what a good job Sedgwick does.
By the way, as lunatic as the song is, they're able to give it a very amusing "twist" ending, so it's worth sticking around all the way through.
For those of you who might be curious about how the song got eventually worked out, here is the final draft version --