The number of people watching videos online has risen, says comScore.

A report by the marketing research company revealed that in the US alone 13.5 billion videos were watched online during October 2008. That's 45 percent more than the same period in 2007. The research also highlighted that 77 percent of US web surfers, around 147 million people, watched videos online during the month.

Net users aged 18-34 were the most common viewers of online videos, with 80 percent of the age category watching content online.

Google alone attracted 100 million unique video viewers, which amounts to more than two out of every three online video viewers. YouTube makes up the lion's share of Google's video offerings, with 99.5 million people watching 5.4 billion videos, on the video sharing site during October.

Fox Interactive was the next most popular site for online videos, attracting nearly 61 million unique viewers. Yahoo, Microsoft, Viacom and Hulu were also popular.

Google users also watched far more videos than visitors to the other sites. On average, visitors to Google sites watched 53 videos. Visitors to Fox sites watched eight.

While user created videos on YouTube make up the bulk of online videos, many of the other sites in comScore's top ten primarily show videos of content originally produced for television or the big screen. Content producers are increasingly offering their products online, although many are still trying to work out a business model for doing so that doesn't cannibalise existing revenues.

See also: MySpace & MTV cash in on pirated videos

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