As promised, SK Gaming have just released their video of their world-first kill of Kil'jaeden. They call this fight "all about absolute perfection in terms of execution," and "definitely the hardest boss ever made and an impressive final boss." Of course, this video contains full spoilers for the KJ fight. I'm just going to assume SK's site will go down, so I'm embedding it from Filefront above, and linking to WarcraftMovies if you want to download it. It's shot from five points of view, though SK promises that it is not "messy" -- hemo rogue, resto shaman, enhancement shaman, and two different destro warlocks.
And since people are always curious, the music used in the video is, according to SK:
Airbase - Ocean Realm
Alex M.O.R.P.H. - Walk the Edge (B2B Woody Van Eyden Mix)
To download in glorious 1680x1050 WMV, head on over to WarcraftMovies (edit: apparently a WCM premium account is required to download the full-res version). An H.264 version is due in a few days.