"Online video coverage of President Obama's inauguration appears to represent a significant incremental audience to TV, since it presumably includes many people at work who did not have access to a TV," comScore's Tania Yuki said in a press release. "As such, the 13 million online viewers during this time period likely represent a 32 percent addition to the reported 40 million people who viewed the inauguration on TV. And, that so much of this online audience flocked to the Web sites of the major cable TV news outlets reflects a direct channel shift from TV to the Internet."

Although countless video sites carried live inauguration streams, 30 percent of those who watched online gravitated toward cable TV news sites, Yuki said. Much like TV, people have a tendency to tune into specific channels when they consume certain content. Unlike TV, online video offers greater flexibility in how, where and when it can provide these experiences. CNN's Inauguration Day partnership with Facebook is one such example. The cable channel created a special version of its CNN.com Live video player that let users comment via their Facebook "status" on what was happening in real time.