From the article: "One of our clients runs a network of very large adult oriented sites, who has agreed to "donate" several of their most popular videos from on

From the article: "One of our clients runs a network of very large adult oriented sites, who has agreed to "donate" several of their most popular videos from one of their sites for this experiment." Assuming you believe that statement it seems they're on the up-and-up as far as copyright goes.