Oh, they're paying at least some of the protesters. They also organize transportation for a lot of them to go to cities where protests are being held.
There was a big A.N.S.W.E.R. anti-war rally here in Houston last February (we FReeped it and really put a blot on their little love-fest; they were quite annoyed with us) and we found out that they had bused in people from Austin, Dallas, Fort Worth and other locations to run up the numbers. There were between 3,000 and 4,000 of the Great Unwashed marching by us.