Right, I remember ppl mentioning it was an open call... I don't think they did open calls previously, but then again, they probably just ran out of caucasians in all the talent agencies. It's no wonder, since I bet not many non-Asians that come to Japan think "Oh, I should sign up to a talent agency so I can be an extra." at once, many people aren't aware of this sort of opportunity (Not me, I wanna go to Japan and do as an extra!
)
But on the other hand, they could just cast people in Japan and them bring the over to wherever the PV was being filmed...