The number of online video watchers in the U.S. increased 18 percent in six months, from October 2005 and March 2006, according to comScore's first-ever study of video viewing habits, writes ClickZ. In March, viewers initiated 3.7 billion online video content streams and on average watched nearly 100 minutes of video content, compared with 85 minutes in October, according to comScore's new Video Metrix service.

Men initiated 52 percent of those streams, women 48 percent, in March, and men spent on average two hours with the content - women, 1.3 hours. Males 18-34 spent the most time with online video, averaging 140 minutes, but all age groups are watching online video.

Some16 percent of video consumption takes place during prime-time hours, and 22 percent on the weekend. Viewers spent about an hour a month watching video while in work locations.