"Holy cow."

For a moment, that's pretty much all Susan Colantuono can say when she thinks about how her life has changed since a presentation she gave last November was posted on the TED website. In the three months since the video went up, the talk has been translated into 15 languages and viewed more than 1.7 million times. Colantuono has been bombarded with LinkedIn requests and invitations to speak at conferences. An agent reached out asking for her book proposal (it hadn't been written yet).

"Holy cow," she says again.

Colantuono, founder and chief executive of the consulting firm Leading Women, was accustomed to speaking before crowds. She's spent the past decade talking with groups of female professionals and at conferences of business executives about ways to get more women into positions of power. Still, it was rare for her talks to get posted online, especially by a channel that has more than 2 billion views.

5.9 million subscribers

But TED, the 30-year-old lecture series that focuses on technology, education and design, has made a mission of giving intellectuals their 15 - er, 18 - minutes of online fame. And it's very, very good at it. The TED network of YouTube channels has more than 5.9 million subscribers - more than any other education channel and plenty of non-education ones (Coldplay, PlayStation, "Talking Animals").

The notion, as TED's motto goes, is that ideas are "worth spreading." Why should the results of someone's research be confined to academic journals and 100-person lecture halls when there's a whole world of Internet users eager to hear about them?

The TED team thinks it's revolutionizing education: "One person speaking can be seen by millions, shedding bright light on potent ideas, creating intense desire for learning and to respond," TED curator Chris Anderson said in a 2010 talk.

The series's detractors say that these videos are a watered-down version of true learning - "middlebrow megachurch infotainment," in the words of University of California at San Diego professor Benjamin Bratton, who gave a talk on the subject at a TEDx conference last year. (TEDx events are independently run offshoots of the main conference.)

So whether TED talks are in fact changing the world is a matter of debate. But for the kinds of people whose work tends to get featured at TED conferences - college professors, social scientists, computer programmers - having a talk go viral can change everything.

Take Susan Cain, a soft-spoken writer from New York who left a career as a corporate lawyer because of the profession's emphasis on extroversion. She gave her TED talk on "the power of introverts" one month into a tour for her first book, "Quiet." Though the book had done well on its own - it debuted at No. 4 on the New York Times nonfiction bestseller list, it was the TED video that turned Cain into something of a celebrity.

"It just blew it out by many orders of magnitude," Cain says.

Less than two years later, the video has been viewed more than 10 million times, and Cain is the inadvertent leader of a "Quiet Revolution" aimed at promoting the contributions of introverts. Now Cain, a self-described introvert, makes her living rallying followers to her "quiet revolution" - exactly the kind of hectic lifestyle she'd fled when she quit law. She's well aware of the irony.

But perhaps she shouldn't be surprised by it. Like the other most-viewed videos on the TED Web site (Cain's ranks 12th), her speech exhibits that particular mixture of personal narrative, theatrics, intellectualism and self-help-style inspiration that the lecture series has perfected. With titles such as "your body language shapes who you are" and "how great leaders inspire action," the most successful talks are life-hacks backed by social science.

Really, messages such as Cain's are made for online video, says Kevin Allocca. The trends manager for YouTube and author of his own fairly successful TED talk ("Why videos go viral" has been viewed more than 1.6 million times), Allocca is an expert in what makes people click.

Although TED talks are somewhat more cerebral than the other viral videos he's seen streaming through YouTube's servers, they share some important qualities with, say, singing cat memes. They offer something unexpected (Jill Bolte Taylor, whose talk is ranked fifth, brings out an actual human brain in hers) and they are usable or participatory in some fashion (Pamela Meyer's, No. 16, promises to teach you how to spot a liar). That unexpectedness factor makes you likely to click, and the participatory factor compels you to share.

Virality also depends on "tastemakers," cultural icons with large followings who can introduce videos to a wider audience. TED, with its wonky optimism and millions of followers, fills that role perfectly.

"When you break down the behaviors, it makes a lot of sense," Allocca told The Washington Post. TED content "is really made for Web-viewing experiences."

That's been the case for his talk, which Allocca says has become a "calling card of sorts." Search "why do videos go viral?" on Google and his talk comes up in two of the top three results. For someone who hasn't written a book or published research in scholarly journals, that seven-minute video is the most visible - and most viewed - display of his expertise. Allocca says many of the people who come to him looking for advice on how to create a shareable video cite his TED talk as the reason they found him.

Colantuono's video, a 14-minute presentation in which she critiques the kind of career advice that's traditionally given to women, has worked in much the same way. The talk is a year old - she had originally given it at a TEDx conference in Boston - and until September had gotten a modest 5,000 or so views.

But then TED, with its 5 million followers, re-posted the video on its own channel. Soon after came the flood of Web site comments, the interview requests, the emails from literary agents.

It's a very particular kind of celebrity, one marked much more by appearances on NPR and invitations to conferences than pictures in People magazine and requests for autographs. Neither Cain nor Colantuono has been recognized outside of their academic context on, say, the subway or at the supermarket.

In fact, sometimes the opposite happens. Waiting in the taxi line at the end of another conference, an audience member chatted with Colantuono about how much she liked a talk, not realizing she was speaking to the person who gave it.

Colantuono laughs it off. She never expected to be known in the first place.