Last year, March Madness on Demand showed every game from the first round to the Final Four, the only major sporting event broadcast live and in its entirety for free on the Internet. CBS had 4.8 million total unique visitors who consumed 5 million total hours of video and audio.

Last weekend, MMOD had 5.6 million unique visitors and 6.5 million total hours of video and audio.

"There's 130 million people watching every year, so we knew it was a huge opportunity to bring it outside of those people just watching it on television," said Jason Kint, senior vice president and general manager of CBSSports.com.

"Last year was the first big kick. We grew 165 percent in audience and this year we're pacing north of 60 percent. We're thrilled with the numbers, but I wouldn't say that we're totally surprised."

The Internet viewership has not come at the expense of television ratings, which CBS executives said were up 6 percent from a year ago.

"The feeds are terrific, the picture quality is great," vice president of programming Michael Aresco said of the On Demand video player. "And, as far as we can tell, it hasn't really cannibalized the ratings.

"It's generating incremental dollars, because the viewership is so enormous."

CBS, which operates the official athletic sites for 215 universities (including 14 of the Sweet 16 teams), has streamed 12,000-plus events this year, including live Southeastern Conference football and basketball games, which executives claim is four times as many as ESPN.com.

CBS rolled out MMOD in 2003 and drew 25,000 paid subscribers the first three years. It seemed to spike with 1.5 million viewers when the network offered it free of charge in 2007.

"We monetize the heck out of it with $30 million in advertising revenue," Kint said. "We did about $23 million in ad revenue last year and we grew that about 30 percent this year.

"As people see more advertisers gravitating to live events like this, we think fans will become more comfortable watching events in other platforms."