The other thing this documentary tells is the story behind several of their songs. This includes "Bridge Over Troubled Water." This song, as most of their songs, was written by Paul Simon. He felt it was perfect for Art Garfunkel. Up until this their songs were duets, with harmony. This song was sung before 1970, but the album and single came out in 1970 and it was voted best song of the decade.
For more Simon and Garfunkel set out these posts:
This movie also has some interesting dialogue with the artists, as well as the producers about the use of echo and harmony. This is a nice presentation. My only complaint is I would have loved less talking and more music.