K i was looking around warcraftmovies and i found this ---
http://www.warcraftmovies.com/movieview.php?id=38202
It is done by mounting up, getting hit by frost nova, sheeped, then cone of cold. Quick use this before it gets fixed! This will probobly be hotfixed in the next patch so have your fun now!
EDIT there you should be able to read the link now.
Glyn