Politicos beware: You live in YouTube's world.

S.R. Sidarth never imagined his 15 minutes of fame would come from a sleepy campaign stop in the southwest Virginia town of Breaks. Or that his handiwork with a camcorder would catapult to the list of most-watched videos on the Web's most-trafficked video site. Or that The Washington Post would devote an entire article to exploring exactly what to call the 20-year-old college student's hairstyle – a mohawk or a mullet? (Answer: neither.)

Sen. George Allen (R) of Virginia also surely never imagined that the young man assigned to track his campaign appearances would cause him days of grief, simply by recording a comment that critics have called "racist" or, at best, "insensitive."

But in the brave new world of YouTube politics, almost anything is possible. And just 18 months after its launch, the website is already playing an integral role in campaigns.

Supporters of Ned Lamont, the Democratic upstart who beat Sen. Joseph Lieberman in the Connecticut primary Aug. 8, discovered that by capturing funny, embarrassing, and otherwise telling campaign moments on video and posting them on YouTube, they could reach voters in a way that's far more entertaining than over-the-top rants by bloggers.

Anyone familiar with the Mentos-and-cola phenomenon – put the candy in the soda and watch it explode – has probably already visited YouTube. But for the uninitiated, YouTube is a free site that allows people to post, watch, and share video clips. By plugging in keywords, as with search engines, users can easily find topics of interest. The searchability is key.

"We've always known the power of video, but now everybody in the world with a cellphone or a small high-res camera and broadband" can get in the act, says Michael Cornfield, an expert on the Internet and politics who teaches at George Washington University. "YouTube is the last link in the system, which is, now 'I can go find it.' "

For several years, political advisers have been instructing their clients to Google themselves and check their Wikipedia entries. "Now the third station of the cross is you've got to YouTube yourself," says Mr. Cornfield. "You have to know just what you look like and how many people are hitting on and redistributing your video."

Already, Web-savvy candidates across the globe are posting speeches, ads, and clips from community meetings on YouTube, though most are best viewed to combat insomnia. Search "Deval Patrick," Democratic gubernatorial candidate in Massachusetts, and 15 titles, such as "Deval Patrick discusses issues of concern to voters in Quincy," pop up. For low- budget campaigns, videos on YouTube are a cheap way to spread the word.

George Allen isn't even the only senator caught on video making an odd comment to an Indian American. Sen. Joe Biden (D) of Delaware appears on YouTube chatting with a young Indian American man about the explosive growth of the Indian population in his state, and elaborates with this: "You cannot go to a 7-11 or a Dunkin' Donuts unless you have a slight Indian accent.... I'm not joking."

Senator Allen's exchange with Mr. Sidarth, a senior at the University of Virginia (UVA), Charlottesville, is more controversial. Last Friday, Allen was campaigning before a crowd in Breaks, Va., and then began addressing Sidarth, the only nonwhite person in the crowd, who Allen knew had been tracking his campaign all week for Democratic opponent Jim Webb. Allen called him "Macaca" at least twice, and then said, "Welcome to America and the real world of Virginia."

Sidarth, who was born in Virginia to Indian parents, handed the video to the Webb campaign, which posted it on YouTube. Thus was launched a political brouhaha that could seriously damage any hopes Allen might have of running for president in 2008, though probably not his bid for reelection to the Senate. Sidarth himself is well aware of the power of the camcorder.

"If I had been there and not had a camera with me, absolutely no one would have believed my side of the story," he says.

The UVA government major says he has yet to hear from Allen directly with an apology, though Allen did issue a statement to the media apologizing "to anyone who may have been offended by the misinterpretation of my remarks." On Wednesday, Allen met with Indian American political leaders to mend fences.

Allen has also said he has no idea what "macaca" means, triggering speculation as to how he came to use that term. The campaign's official explanation is that it was a version of "Mohawk," the nickname campaign workers had come up with for Sidarth, based on his hairstyle. Unfortunately for Allen, he chose a word with various meanings: It is the genus for macaque monkeys. In Europe, it can also be a slur against African immigrants.

If nothing else, the widely publicized flap has put all politicians on notice that they can never let their guard down. That pesky constituent following you all the way to your campaign bus may be wielding a recording device, and it's best to remain polite. Conveying context can still be problematic with videos. And there's always the possibility of technological trickery, à la Photoshop. But this new ability to post and share videos is nothing short of revolutionary in the political world of message management and image making.

Says Cornfield: "There's nothing in our world that seems to have the immediate impact of seeming to convey the whole truth and watching something come out of somebody's mouth, [with] your own eyes."