Check out this video guys. It is made by a GM who amazingly had access to his powers even on the PTR. (I still don't know how he managed to do so).
http://www.youtube.com/watch?v=AtxnxArDe84
I am really surprised by the fight mechanics. it involves lots of moving around and handling packs of one or two adds who does extremely surprising moves eventually.
The fight even includes some epic dialogues between the Lich King, Adds and Players.
check it out.
EDIT :
Oh guys I accidentally posted the wrong link
here is the right one :
http://www.youtube.com/watch?v=5oHkjoE-os8
it is more of a trailer. but still shows some aspects of the fight.