Financial Times explains that once the ID system is in place, Facebook will work with record labels on a licensing deal for all the music that's available on the site. Those talks are said to be in the early stages and a final agreement isn't expected before this spring.
The music industry has been taking issue with YouTube for years, claiming that the site doesn't adequately compensate artists and rights holders for the content it hosts. Earlier this month, the video site announced that it paid $1 billion in ad revenue to the music industry in the last year. Facebook has revenue deals in place with publishers, but doesn't currently have any licensing agreements for music. As you might expect, labels want a piece of that ad money like they're receiving from YouTube for having their music available to users.
According to a National Music Publishers' Association op-ed on Billboard this fall, the songwriters' trade group said it identified nearly 900 videos that contained 33 top songs on the music charts at the time. Those clips garnered well over 600 million views total, so it's easy to see why the music industry wants to be compensated for having its material on display in Facebook videos.