Online advertising rep firm Gorilla Nation  plans to open offices in the United Kingdom and Australia this year and will officially launch a new video platform next month.

“It’s an effort to source additional revenue by tapping into a new advertising base and new publishers,”  said President Brian Fitzgerald about the new office openings.

This follows a bumper year for the Los Angeles company, which doubled in size during that time and signed on more than a dozen new web publishers, bringing the total it represents to more than 550. It already has offices in New York, Chicago, and Toronto.

Gorilla Nation focuses on those web publishers' sites that aren’t big enough to warrant an in-house ad sales team but still see enough traffic to be of interest to big-name brands.

GNSpringboard, Gorilla Nation’s new syndicated video player, will officially launch in March. It will add to the growing list of products the company offers to online advertisers through its “Mid-tail Toolbox.”

Online video is exploding, with more than 50 percent of the U.S. population expected to use the medium this year, according to eMarketer. Ad dollars predictably are following the trend. The research firm forecasts U.S. online video ad spending will reach $3.1 billion by 2010 from less than $1 billion last year.

But Mr. Fitzgerald said that advertisers struggle to place video ads because there are so many incompatible video ad serving platforms. Advertisers can produce a video ad, but its format will limit where it can be published.

Gorilla Nation is hoping to bridge that divide by offering its network of publishers a single platform that not only serves video but also photos and interactive games. It will also work like a widget, said Matt Stodder, VP of ad strategy for Gorilla Nation, meaning users can take the content and embed it in their own blogs or social-networking sites.

“I think Gorilla Nation has correctly observed the pent up demand for video ads that can’t be effectively delivered,” said Gartner analyst Andrew Frank.

But he cautioned that the company will be competing against big names like Google’s DoubleClick and Microsoft’s Atlas to get publishers to adopt its video platform, in addition to a host of other ad rep firms focused on the mid-tail.

Gorilla Nation announced on Friday that former venture capitalist Bill Foltz has been named CFO. The company is privately held and had a $50 million, first round of financing by Great Hill Partners in May 2007.