Mark Cuban, who cheers on Viacom's $1bn suit against Google as enthusiastically as he supports his Dallas Mavericks, is the loudest defender of copyright ownership that the media companies have. And he's credible, because he's a former internet entrepreneur, without an obvious vested interest. But has anyone asked why he's so personally invested in the battle against Youtube? Cuban's fortune comes from the $5bn sale in 1999 of Broadcast.com, an early video aggregator, to Yahoo. Every successful entrepreneur resists the notion that their success was merely a function of fortunate timing. Broadcast.com never had even a fraction of the audience of Google's Youtube. But what it did have was a set of internet broadcast rights. I suspect it galls Cuban that Youtube has garnered such popularity, so quickly, while he painstakingly negotiated with content owners, to build a site which quickly disappeared within Yahoo. He may not have Viacom's economic interest; but he has a strong psychological motive to bash Youtube, Bittorrent, and every other video sharing technology that's emerged since his day.