It may come as no surprise to many who spend a lot of time on Google's popular video Web site YouTube, but the service accounts for one out of every three videos viewed online. Market research form comScore said that YouTube accounted for over three billion of the over nine billion videos viewed in January 2008.

While nine billion videos is certainly a lot of viewing, that number is actually down from December. In a record-breaking month December 2007 saw over 10.1 billion videos viewed online.

However, Google sites gained 1.7 percent market share to 34.3 percent or 3.4 billion videos viewed -- YouTube account for 96 percent of Google's videos. Fox Interactive Media ranked second with 584 million (6 percent), followed by Yahoo! Sites with 315 million (3.2 percent) and Microsoft Sites with 199 million (2 percent).

According to comScore, more than 139 million U.S. Internet users spent an average of 206 minutes per person viewing online video in January. Google Sites also attracted the most viewers (80 million), where they spent an average of 110 minutes watching video. Fox Interactive attracted the second most viewers (53.9 million), followed by Yahoo! Sites (36.3 million) and AOL LLC (21.9 million).

The research also showed that more than three-quarters of the total U.S. Internet audience (75.7 percent) viewed online video.