The Song
Dancing Mad is the final battle music of the role-playing game Final Fantasy VI. Clocking in at over seventeen minutes, it's easily the longest final battle music of all Final Fantasy games (unless I'm wrong?). Anyway, it's so long because there are four "movements" to the song, one for each boss tier. The song contains several remixes of other songs in the game, such as the opening theme being used right before the final tier's music.
The song was also covered by The Black Mages, Uematsu Nobuo's (the composer of most, though not all, Final Fantasy music) band. This version is about eleven minutes long and is basically a "rock" version of the song. I don't know anything about music, really, so I can't tell you any details.
More info will come later when I have enough time to make some content.