World of Weird Al Yankovic

Last album, I believe that amazon.co.uk was the first site to provide 30 second previews of the songs on Alpocalypse. With only one week until MF, there is still no sign of previews. Who is in charge of that? Are websites given these previews by Al's record company and told to release them on a certain date, or is it just free will of those websites to post them?

Bermuda already answered that here.