Variety reports that Google's YouTube unit has reached a deal with Twitch.tv to buy the game-streaming service for $1 billion. From the article: "The deal, in an all-cash offer, is expected to be announced imminently, sources said. If completed the acquisition would be the most significant in the history of YouTube, which Google acquired in 2006 for $1.65 billion. ... YouTube is preparing for U.S. regulators to challenge the Twitch deal, according to sources. YouTube is far and away the No. 1 platform for Internet video, serving more than 6 billion hours of video per month to 1 billion users worldwide, and the company expects the Justice Department to take a hard look at whether buying Twitch raises anticompetitive issues in the online-video market."