I'm not sure if this is the one you are talking about, but there was a post with cats meowing Silent Night. It was adorable!! It was right before Christmas and I remember the title of the thread was something like Happy Holidays or Merry Christmas from Denmark. I remember that because I went back to it several times. It was so cute and it drove Leroy crazy!!!
I'm sorry but I'm at work right now or I would take the time to try to look it up for you. I hope I was of some help!
This wasn't a video though, it was just a sound track.