Visitors to MTV’s new online music video site can listen to songs with plenty of crass and vulgar lyrics, but may be surprised to find that certain other language had once been deemed too nasty for broadcast — that is, the names of the file-sharing sites Morpheus, Grokster, Limewire and Kazaa, all of which have been the bane of the music industry. The foul-mouthed musician swept up by MTV’s speech code is Weird Al Yankovic, whose lyrics to “Don’t Download This Song,” a tongue-in-cheek complaint about file-sharing first released in 2006 included those so-called offensive terms. (Since then, two of...