(I didn't forget yesterday, I just usually keep myself off the web on Tuesdays.)
"Hark" by Israel & New Breed
This must be the most musically complex version of any Christmas song. Even if you know next to nothing about timing and chord progressions (like me), it's still captivating. And yes, the video image is completely black all the way through. It only contains the audio of the song. Kinda nice, really.