In case you were wondering why there are so many start-ups doing social video sharing sites, it isn't just to provide horny animators a place to host their creations.

Why then?

Reason 1. People are consuming video through the web and on mobile devices in record numbers. Softbank recently invested 5.6M in Purevideo, who has some amazing viewership stats among youth:

SoftBank Capital, the U.S. VC group associated with SoftBank Corp., is investing $5.6 million in LA-based PureVideo, a digital media company specializing in online and mobile user-generated content. The company says it streams more than 84 million downloads a month to 5.8-plus million users via sites StupidVideos.com and GrindTV.com. StupidVideos is one of the largest video sites, according to Accustream iMedia Research.

Om Malik on Heavy.com:

Heavy.com gets about 10 million unique visitors a month, and is the 7th fastest growing web brand by Nielsen-NetRatings. My favorite program on Heavy network is "Behind the Music that Sucks." The company was started way back in 1999, and has gone through some makeovers, but with broadband usage on an upswing, Heavy has finally found momentum.

With these kind of viewership numbers, they may eclipse the new CW network. I'd put money on it. And, more importantly, so are advertisers...

Reason 2. Online video advertising is booming:

The online video ad spending forecast was a portion of the overall rich and streaming media spend projections announced at the Jupiter/ClickZ Advertising Forum Conference in New York today. The research firm expects the market to nearly quadruple from $1 billion in spending in 2004 to $3.8 billion in 2009.