An unsigned rap group called After the Smoke couldn't post their song "One in a Million" to YouTube because every time they tried, it generated a YouTube content-match error saying that Universal Music owned their song. It turned out that UMG had laid claim to a leaked video that had a UMG artist performing the unsigned band's track in it, and this effectively gave Universal the power to censor the unsigned band's song.
YouTube's content-matching system has a lot of problems, as archivist Carl Malamud discovered when corporations started to claim that they owned the public domain US government videos he posted, threatening to cost him his YouTube account. And Universal attained notoriety for abusing content match by claiming to own the song that MegaUpload commissioned from major artists criticizing Universal and other rightsholder groups for their copyright stance.
Universal Music May Have Inadvertently Exposed a Flaw in the YouTube Takedown Process