The video: World of Warcraft Big Blue Dress
was added to YouTube by Phenixxx. It does not contain any claim in-video or description as being created by Phenixxx, Credit in the closing scenes (not explained whether for music/video or both):
"Big Blue Dress"
As it happens, further research suggests that Cranius is also responsible for the video and music, and apparently vocal and character performance too. I'm curious, though I don't play the game myself, about the source of the dwarf back-up singers: are they Cranius-alts composited, or friends/guild members?
So surely the reference for this would be:
Cranius. (2006). Big Blue Dress [music video]. Retrieved May 18, 2007 from http://www.youtube.com/watch?v=vqO7zEWu0W0