Poke around on Yahoo! a bit, and you'd think online video advertising is already flourishing. A trailer for the latest Harry Potter film is prominently located on Yahoo's home page. On the portal's food site, there's a Hellmann's mayonnaise ad that features a video of a man steaming salmon on his car engine. And a search for "funny videos" reveals an entire Yahoo channel devoted to online commercials.

But a new report by eMarketer, released July 16, suggests Web surfers ain't seen nothing yet. Video ad sales are expected to grow from an estimated $775 million this year to $3.1 billion in 2010 and then to $4.3 billion in 2011. That's up from a November projection in which eMarketer estimated 2010's video ad sales at less than $3 billion.

Though the numbers sound large, the expected activity over the next four years suggests that advertisers will be merely experimenting with the medium. Even at $4.3 billion, spending on video ads would account for just $1 of every $10 of Internet advertising.

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