Not only have sites like YouTube made it possible for numerous unknown adolescents to be discovered — Greyson Chance, a 13-year-old from Oklahoma, got a record deal after Ellen DeGeneres mentioned his YouTube piano version of Lady Gaga’s “Paparazzi” on her talk show, for instance — but youngsters with no special talent, like Ms. Cinkle, are drawing mass followings as well. (The publicity wave that fueled Ms. Cinkle’s popularity was, in fact, driven overwhelmingly by viewers who hated the video she was performing in, routinely calling it “the worst song ever” even as they watched and forwarded it en masse.)

Trevor Michaels, 12, better known as iTr3vor, has received more than 5.5 million views on his YouTube channel for hyperactive dance moves he performs at various Apple stores when his mother takes him shopping at the mall. (He uploads videos of the dances on the spot.)

Then there are the legions of girls who post “haul” videos, short clips of themselves chattering about their most recent fashion and makeup purchases. The spots are unwatchable to most any adult, but they draw in hundreds of thousands of girls in their teens or younger who are eager to duplicate the shopping habits of their peers.

YouTube, the global video-sharing site, estimates that 10 percent of its most-subscribed users are 19 or younger and that, as a whole, more than one-third of the most successful participants in its revenue-sharing Partner Program are under 25. “It’s fascinating to see how many of the kids who have huge followings are almost going under the radar of most adults,” said Annie Baxter, who works in the partner program and recently helped oversee how-to courses for nascent YouTube stars at Google’s Manhattan offices.

For every success story, there are thousands of other teenagers poised and eager to seize their own moment, should it come. “Every teenager is already creating unique content for a multitude of social media accounts,” said Valerie Veatch, a filmmaker who is directing, with the artist Chris Moukarbel, a coming YouTube documentary, “Me At the Zoo,” which takes its title from the very first clip uploaded to the video-sharing site in 2005. “And in a way, constant social networking serves as training in the event that your content blows up on the Web. You’re prepared to engage the expectations of fans.”