This is the next step by Google to help remove websites that are making money by posting pirated content and links to pirated music, movies, etc.
This move has apparently been made by Google as "Rights holders" have accused Bing as well as Google of providing links to pirated versions of songs or movies rather than the legal downloads available via Search. By limiting funding Google will be able to get rid of pirated websites without having to change its search algorithms.
This approach was also taken against Wikileaks in 2010 by Visa and MasterCard when it had leaked 250,000 classified cables from the US embassies. However, the payments had to be processed later on as stated in a court order.
According to the Telegraph, Google is working on first round of discussions to implement this plan. It has been said that Google may enact on this strategy as soon as April this year.
Initially the sites with pirated content will be sent legal challenges to stop the piracy and if they do not respond then future payments from customers will be blocked for them with the help of Paypal, Visa and Mastercard. Google is still a little cautious of implementing this strategy as some websites may use this strategy to shut down competitors by accusing them of pirating content.