Mozilla Corp., maker of the open-source Firefox browser, launched on Thursday the second phase of its fan-powered marketing campaign, calling on professional or amateur filmmakers to compete for the best broadcast-quality 30-second commercial for Firefox.

Entries to the Firefox Flicks Ad Contest would be judged by a panel drawn from the film, television and advertising industries. Judges include Freddy Rodriguez, actor for the HBO show "Six Feet Under;" Ben Younger, writer/director of the movie "Boiler Room;" Warren Zide, producer of the movie "American Pie;" Scott Goodson, chief executive of the Strawberry Frog ad agency, and others.

Earlier this month, Mozilla launched the first phase of its Firefox Flicks campaign, which was a testimonial Web site in which fans could sing the browser's praise in short videos. To date, several dozen of the amateur clips, which vary widely in quality and have been submitted from more than 20 countries, have been posted on the site.

Winners in the latest marketing ploy will be eligible for prizes, and their ads could end up in future global marketing campaigns for Firefox.

The Flicks campaigns are a reflection of the grassroots marketing that has driven much of Firefox's success over the last year. Marketing tactics have included encouraging fans to spread the word, savvy use of Firefox websites and the sites of supporters, and some keyword advertising on major search engines, such as Google Inc.

Those efforts have built a user base of more than 50 million people worldwide, Paul Kim, director of product marketing for Mozilla, said.

Nevertheless, to capture a bigger share of the general online population, the majority of whom are less technically savvy than the typical Firefox user, Mozilla will need to add to its marketing strategy.

As a result, the company is looking at all forms of potential advertising, and hasn't discounted the use of offline vehicles, such as TV or print.

"We're in the process of defining the marketing plan for Firefox for 2006, and all options are on the table," Kim said.

Mozilla, the for-profit subsidiary of the nonprofit Mozilla Foundation, is also looking to convince manufacturers to include Firefox in their PCs. Kim declined to name any companies, but said, "We are aggressively pursuing distribution opportunities."

In the meantime, Firefox remains a small player in the browser market compared to leader Internet Explorer from Microsoft Corp. In October, Firefox had an 8.59 percent share, compared with IE's 86.52 percent, according to Web monitoring firm NetApplications.

Market share numbers, however, do vary significantly, with other researchers saying Firefox has more than 10 percent.