Apr 6th 2007 2:49PM @10, At the time, Kazzak and Azuregos where the only world bosses around. The guys that did this were working on Azuregos shortly afterword with several pallies* but the horde came to kill him before they had the chance to finish.
Additionally, this required the ability to duel to stack up the reckonings, which ruled out doing this in an instance (which at the time were only Molten Core and Onyxia).
@5, there are higher quality versions of this video available from WArcraftMovies.com:
I will dig up the source video used on this so you can see the names and give homage to those who actually participated in the event. (I made an effort to block out the names involved so that no one would get banned or anything like that).
* Kazzak had something like 175k HP, while Azuregos is closer to 700k HP. Considering this took three hours of critting to get the sufficient number of reckonings stacked, with a single pally Azuregos would take on the order of 12 hours of sitting there being crit.