I didn't know this existed: it's the voice tracks from some Beach Boys tunes. Remove the music and you can really appreciate their harmonies - which were great to begin with.
I've always liked the Beach Boys, but this has boosted my appreciation for their talents and style of music.
There isn't supposed to be any instrumental music, but if you listen carefully, particularly to the "Sloop John B" track (and the not-so-great "Caroline No"), you can clearly hear the tune. perhaps it was sound bleeding from someone's headphones into the mic.
Regardless, it's a great piece of music. The second half of "God Only Knows" made me think of a wedding procession tune.
...There's that word again....