It really looked to me like they were all really there. I imagined the trials that their production staff must have gone through to a) actually get hold of each of them and b) convince them that they *actually were* from the company doing Weezers new video. And then for some, explaining who Weezer are :) Still, fabbo.
http://www.spikedhumor.com/articles/42134/I_Wanna_F_You_In_The_A.html
(not that SFW)