In December 1990, at perhaps the peak of Simpsons Mania in the US, the show's first tie-in album, The Simpsons Sing the Blues, was released, a mixture of covers and original songs performed by the cast in-character (accompanied by several well-known musicians). The album spawned several singles, plus the music videos for "Do the Bartman" and "Deep, Deep Trouble" (the former of which was likely the introduction for several of the show's British fans, receiving an outing on Top of the Pops some years before the BBC would win the rights to the show itself), and was the inspiration for several similar albums from other franchises such as Dinosaurs.
Around 1992, a follow-up along very similar lines was recorded, The Yellow Album... which was then repeatedly postponed and put on the shelf until it was finally released in 1998, for unclear reasons (also putting the kibosh on the idea of any more music videos, which some songs from TYA would have had had it been released as originally scheduled). Not only that, but even if you own The Yellow Album, you do not have the songs as originally intended; when it was finally released, half of them had had their tempo and pitch noticeably sped up, several others were edited in some way, and one song (the Prince parody "My Name is Bart, And I Am Funky") was removed altogether. The Simpsons Archive has a fine list of all the differences between the original test pressings and what actually made it to the shelves.
For a time, MP3s apparently taken from a test pressing were available online, but they seem to have disappeared now, leaving this "original" version of the album lost for the last few years (if not decades). I was quite surprised, then, to find this on a recent YouTube search: what appears to be an excerpt from the song that was cut entirely (it runs to 2:29, but the Archive gives the time for the full song as 4:54). If anyone in the know can confirm for certain that that video is indeed part of "My Name is Bart, And I Am Funky", that would be welcome (I realise it's difficult to see what else it could be, but absolute confirmation for sure would just be nice).
And: Do those original versions of the other songs still exist anywhere? (I've had a go with the Wayback Machine but have had no luck beyond this contemporary piece on the album's release, and discovery of the bootlegged test pressing.)