Mark Cuban, the Dallas Mavericks owner who made a fortune pioneering audio and video broadcasts on the Internet, is banking on high-definition TV as the next big thing. Last September he launched HDNet, the only national network to broadcast exclusively in high definition, and sports events make up 25% of his programming. HDNet carried 65 NHL matches and a handful of NBA games in 2001-02. This season 80 major league games will be aired. Says Cuban, whose channel is available only on DirecTV, "We can redefine how people watch sports. Watching hockey, basketball, baseball, football and boxing are completely different experiences in HDTV."