Help!

[XxZzombiexX]

Hey guys, so I'm a musician. I play Alto Saxophone, Piano and I can sing. However, I can not play by ear. I am planning on singing 'O Holy Night' for my Christmas concert at school. I need the chords to this version of it

http://www.youtube.com/watch?v=8G84I42pJ3g

I need it soon so if anyone can help me out, I would really appreciate it!
Thanks a million.
Yours truly,
Zzombie<3

[AkaTsuki-chan]

What key do you want it in?