CBS Corp.’s experiment to offer free online coverage of the NCAA men’s basketball tournament drew big numbers during the first two rounds, serving more than 14 million streams of the live broadcasts.

Peak viewership occurred on the tournament’s first day, particularly from people checking in from work, according to data from Nielsen/NetRatings. On Thursday, the CBS network of sites attracted 2.5 million unique visitors from work compared with 1.3 million from home.

“There have been in the past, and there will be going forward, concerns about the effects of major sporting events on worker productivity,” said Jon Gibs, senior director of media for Nielsen/NetRatings. “Workplaces, however, should consider that many of these same workers could just as well be taking long lunches or repeatedly refreshing browser windows to see new scores. So while video is certainly not adding to worker productivity, the jury is still out on its negative effects.”