This was a cool little fan video I found. The sprites have been touched up a bit but not redrawn, it's mostly the audio and some editing that makes it interesting.
Final Fantasy VI: The Dream Oath Opera - Maria and Draco (Aria di Mezzo Carattere) - YouTube
For those wondering why the cast of VI never show up, apparently they actually wrote a finished version of the opera in Japan for one of the Distant Worlds album, so this video shows a hypothetical conclusion to the opera and it's pretty damn awesome if you ask me.