The author of the original post (Andy Baio) found exactly where the line was. He released a (great) chip tune version of the jazz classic Kind of Blue (named Kind of Bloop), fully handled the music copyrights, and was promptly sued by the cover artist for Kind of Blue who believed that the pixel art cover of Kind of Bloop was not adequately transformative.
https://waxy.org/2011/06/kind_of_screwed/