If you think that Google's (NASDAQ:GOOG) market position in search is impressive, just check out its dominance among video-sharing sites.

Fueled by the mighty juggernaut of YouTube, new rankings from market watcher comScore reveal that no one's even approaching Google when it comes to online video.

Source

Nov. Views (in millions)

Market Share

Google

5,373.8

39.7%

Fox

519.9

3.8%

Yahoo!

363.4

2.7%

Viacom

305.3

2.3%

Microsoft

286.5

2.1%

Source: comScore Video Metrix. Data for October 2008.

That actual 39.7% market-share slice may not impress you, but in this highly fragmented market, Google still draws more than 10 times the traffic of its nearest competitor. News Corp.'s (NYSE:NWS) Fox clocks in at a distant second, thanks to the video-sharing functionality of MySpace.

Don't assume Google's unassailable, though. Three months ago, Google was commanding a thicker 44.1% slice of a smaller viewership pie. Since then, Yahoo! (NASDAQ:YHOO), Viacom (NYSE:VIA), and Hulu have all grown their market-share slivers, at the expense of laggards like Google, Microsoft (NASDAQ:MSFT), and Disney (NYSE:DIS).

OK, so maybe calling Google a "laggard" is a bit extreme. YouTube is a category killer, with Google attracting a record 100 million of the 147 million stateside consumers of online video.

That may not seem to mean a whole lot right now, given how poorly the leading sites have fared in monetizing their videos, but their luck in that regard is slowly changing. Even movie studios like MGM are signing up to be YouTube partners, and contributing content in revenue-sharing deals. Yes, there's actual revenue to share! The site has been busy optimizing its ad-serving opportunities without alienating viewers.  

Monetization will be YouTube's biggest challenge. However, with so many people watching, it's an opportunity clearly worth fighting for.

More YouTube clips:

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Microsoft is a Motley Fool Inside Value selection. Google is a Motley Fool Rule Breakers pick. Walt Disney is a Motley Fool Stock Advisor recommendation. Try any of our Foolish newsletter services free for 30 days.

Longtime Fool contributor Rick Munarriz is ready to officially classify himself as a clip-culture junkie. He does not own shares in any of the companies in this story, save for Disney. He is also part of the Rule Breakers newsletter research team, seeking out tomorrow's ultimate growth stocks a day early. The Fool's disclosure policy is now available in widescreen.