As rush-hour traffic rolled by outside on East Carson Street Friday evening, the staff at Pittsburgh Guitars locked the doors and began shooting a mini-drama inside.

Lake Fong, Post-Gazette Carl Grefenstette, owner of the Pittsburgh Guitars store on the South Side, films a commerical video of John Bechtold, left, and Sam Matthews playing guitar. The video, shot last Friday, has been posted on YouTube.com. Click photo for larger image. View these videos on YouTube: Pittsburgh Guitar's "Is It Him?" Pittsburgh Guitar's "Your Bob Is Good Here" YouTube founders' message

It was theater in the rough. Employees played the main roles, the basics of a script were written earlier that day and the videographer was the store owner who kept making up lines on the spot, adding almost gleefully, "That's how it goes. Show biz."

The resulting video was destined for YouTube.com, the free online video-sharing site that has become a favorite bulletin board for everything from silly clips showing women doing the chicken dance in their car to fan videos of rock concerts and clips of professional TV commercials. It has become one of the hottest sites on the Internet, reportedly drawing 72.1 million unique visitors in August, versus 2.8 million the previous year -- and a $1.65 billion takeover offer this week from Google Inc.

Not bad for a concept founded less than two years ago by co-workers, one a graduate of Indiana University of Pennsylvania. "Our community has played a vital role in changing the way that people consume media," Chad Hurley, YouTube chief executive officer, said in the statement after Google's deal was announced.

One community particularly interested in YouTube has been the advertising and marketing world, where the site's mixture of usefulness and hipness have attracted small businesses on a budget and big companies looking for ways to make their commercials available to viewers anytime.

For example, just a little over a month ago, the man responsible for the 1-800-My-Lemon jingle familiar to many Pittsburghers discovered YouTube -- thanks to his 15-year-old daughter. Now Larry Hall, general manager of the Pittsburgh office of Small Business Television, a Marshall business that makes commercials for small companies, has posted on the Web TV commercials for businesses such as Wildwood Highlands, Laketon TV Sales & Service and Living Treasures Animal Park.

Posting spots on YouTube is a lot easier than sending large computer files that many people's computers don't have the technology to open, said Mr. Hall. After years of lugging around VHS players and large laptops to client offices, he marvels, "I've sat on the couch and uploaded these from my laptop."

Advertising agency TenUnited, with offices in Pittsburgh and in Columbus, Ohio, has become a minority investor in a Columbus-based online site called MoQvo that launched in June and pulls together video, audio and text content from all over the Web, including YouTube. MoQvo's plan is to help advertisers use the new technology to develop TV-like offerings on the Internet.

As for the Pittsburgh Guitars store staff, it began having some fun after an employee found YouTube was a great place to see clips of bands. A businessman of all trades, store owner Carl Grefenstette also happens to have a company called Worldwide Filmworks that had editing and film equipment, making it easy to experiment with YouTube.

The store's staff made a video called, "Is It Him?" where a rather Ozzy Osbourne-like character is checking out the store and another called, "Your Bob is Good Here," where a George Harrison-like figure is trying to pay in English currency.

The only consistent theme tends to be having fun. "We're not trying to reach anybody," insisted Mr. Grefenstette. "We just do stuff to entertain us."

So far, the clips have each been viewed less than 200 times, according to YouTube's posted information. That's far less than the more than 300,000 who watched the message that the YouTube founders posted yesterday after Google's purchase was announced.

But Pittsburgh Guitars does sell over the Internet and if there's a way to get out the store's name, and perhaps a sense of its studiously noncorporate image, that's not such a bad thing.

The newest video is meant to start a sort of mini-series in which a tall Marshall amplifier -- that's right, a big electronic device -- discovers guitar player John Bechtold has done a gig with a smaller amp.

In the second one, the Marshall amp may be seen in a nearby bar drowning her sorrows. The third, she may come ask Mr. Grefenstette for a job and so on.

"I may try picking up the amp on the rebound," joked Sam Matthews, another employee.

YouTube plays host to bigger budget commercials, too.

Type in Volkswagen or Budweiser on the site's search function and numerous clips show up. Some may not be legitimate ads, but that adds to the "cool" factor. More than a few companies post their commercials on the Web site before the campaigns break nationally, hoping to create some buzz as people e-mail links to their friends.

Companies have so far tended to allow posters some leeway, hoping the benefits outweigh the risks. In a world where traditional systems of marketing are becoming less effective, advertisers are trying to figure out which of the new tools will help their brands.

Pittsburgh-based H.J. Heinz Co. has not officially posted any commercials on YouTube, but a search turns up spots from the United Kingdom and Australia that helpful viewers have put up. There's one for microwaveable soup that probably wouldn't fly with an American audience but worked for the British sense of humor.

"It should be noted that many of the commercials are not official company spots," said Heinz spokesman Michael Mullen. The soup one was real, he said.

Correction/Clarification: (Published 10/11/2006) Larry Hall's name was misspelled.