I understood the comment before me differently: I thought it was criticized that the content providers (people putting videos on YouTube) would expect something in return, not that YouTube & Co would expect a payment of sorts. I know that Social Webpages are not really free.
(This will all change very soon, when people are ready to start paying for a higher - and much more private and secure - level of premium service. You know, the Web will evolve to resemble the "regular' economy more and more, I believe..)