Turning the ocean of free, ad-supported music videos on YouTube – including many amateur renditions of popular songs – into a subscription service where music labels and artists get their rightful cut of the revenue is tricky, both technically and contractually. The labels are already unhappy about the amount of free music on YouTube, and the rise of other popular paid streaming services like Spotify has given them more leverage in negotiations with YouTube.
Source: YouTube Chief Pushes Ahead with Subscriptions Despite Questions – Digits – WSJ