Among the thousands of results for “Brooklyn” on the video sharing Web site, YouTube.com, a two-minute short titled “338 22nd St., Bklyn NY—Illegal Work Part 2” is buried deep among the pages of results.

The video, shot a night, is shaky, dark and blurry, though two men can be made out hacking away at a rooftop chimney with a sledgehammer.

“This is great—now they’re just taking debris and throwing it off the house into the backyard,” says an off-screen voice. “Now he’s taking down the brick chimney, no hardhat — nothing. This just keeps getting better and better.”

The voice belongs to the cofounder of the Concerned Citizens of Greenwood Heights group, Aaron Brashear, who posted the video online and submitted it to the Department of Buildings in January in an effort to push action against the workers who he claims were doing demolition without a permit.

After receiving the video, the city sent an inspector to the site at 338 22nd Street, near Park Slope, where the owner was issued a violation for working without a permit, according to the department. Mr. Brashear, who also catalogued workers at the site bagging up asbestos-laden material allegedly without a permit, claimed victory with the action.

A spokeswoman for the owner of the site, LD Development LLC, said the workers had a permit, and the violations are being worked out with the city.

Frustrated with what he calls slow response times from the Department of Buildings, Mr. Brashear has become something of a video vigilante when it comes to illegal demolition, capturing on film contractors who carry out unauthorized demolitions and are long gone before a building inspector arrives hours later. Along with his wife, Mic Holwin, he has posted eight similar videos on YouTube and started a play list where other Brooklynites can submit their own home movies of contactors possibly violating demolition rules.

His actions have helped to get the city to issue violations on a handful of properties in his neighborhood, Mr. Brashear said. New to the use of video complaints, a spokeswoman for the Department of Buildings said the department can issue a violation based on video if coupled with a signed affidavit by the producer.

“My wife and I have started to carry a camera with us everywhere we go,” Mr. Brashear said. “We see stupid stuff every day.”

The actions of Mr. Brashear and his camera-wielding neighbors come at a time when new development is spreading south through Brooklyn. Due in part to comparatively restrictive new zoning regulations in parts of Park Slope, community members say more developers are now interested in their neighborhood. Community District 7, which includes Greenwood Heights, saw 192 applications for building permits in January, up from just 44 from three years earlier, according to statistics on the Department of Buildings Web site.

The rapid pace of construction has caused concern among neighborhood activists, who are stepping up efforts against big proposed developments through legal action, among other measures. Along these activist lines, Mr. Brashear sees his amateur videos not only as a tool to fight developers who violate building code, but as a means of pointing out an inadequacy with the city’s method of enforcing that code.

“They won’t witness anything going on, and thus they can’t give fines,” Mr. Brashear said of the city inspectors.

A City Council Member of Queens, Tony Avella, who serves on the Housing and Buildings committee, said some developers and demolition crews skirt the city’s regulations intentionally, aware of the slow response time by inspectors.

“By the time the inspector gets there, it’s over, and that’s what the developers who do this construction are relying on,” Mr. Avella said.

The ease of getting away with a violation comes in part as a result of a strained DOB, he said, which is dealing with record numbers of complaints.

The Department of Buildings, which said it investigates all complaints, saw the number of construction-related complaints in 2006 rise to 97,000, up from 47,000 in 2002.

While the number of construction inspectors citywide has increased in Brooklyn, it has not been proportional to match the rapid rise in complaints. The 37 inspectors devoted to the borough today is about twice what it was in 2002, though the number of complaints filed has nearly tripled.