Here’s what seems to be the story. A bunch of recording artists (such as P Diddy and Will.I.Am) recorded a song in support of MegaUpload, a file transfer site that had run afoul of the labels. UMG brought a DMCA to take down the video It’s still down on YouTube, I’m embedding the Vimeo version.  There’s speculation that UMG’s theory may have been that one of the artists in the video was under contract to assign UMG all works he creates.  I’m not sure that satisfies the written assignment requirement.
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MEGA UPLOAD SONG!!!! BROUGHT TO YOU BY OKFOCUS! from OKFocus on Vimeo.