This is old, but still awesome, so I decided to upload my version as there's not a lot of videos regarding this on YouTube. I did found a great subbed and translated version : http://www.youtube.com/watch?v=DbczWczlXUo Thanks at the maker MuchitsujoRyu! (we are also able to see who's singing in that one)

If you're looking for the proper off-vocal karaoke version, it can be found on dailymokyon from haruhi.fr : http://kyon.haruhi.fr/video/221

About Nico Nico Douga : http://en.wikipedia.org/wiki/Nico_Nico_Douga
About Kumikyoku Nico Nico Douga : http://en.wikipedia.org/wiki/Kumikyoku_Nico_Nico_Douga

I love the spirit of these videos, it's the absolute height for us otaku people. The best we can wish for... that makes us feel stronger as never.
It's popular on Nico Nico Douga, but I wish it would be more popular to Japan lovers in here.
And above all, I wish I could gather people to sing it together at the next anime convention!