Stealth advertising — an ad-industry buzzword for a few years now — is so low-key it doesn't look like advertising at all.

Turns out it's also fairly recession-friendly — because it's cheaper than traditional TV advertising. And when it works, it's usually the kind of thing that really works.

Take that popular Web video of guys jumping and swinging and back-flipping into their jeans. It was paid for by Levi Strauss & Co. — at a fraction of the cost of a TV commercial.

Levi's then paid a relatively modest fee to Feed Co., which planted the video — and a conversation about it — on the Web. The video has been viewed about 14 million times, according to Feed.

"Your marketing — if you're successful — is going to be done by your audience," explains Feed Co. executive Josh Warner. "It's where you're getting return on investment that can really explode through the roof."

The media helped promote Levi's stealth advertising campaign by showing or writing about the jump-into-jeans video. It was featured in the online versions of the Wall Street Journal and The New York Times, and on David Letterman, MSNBC and Good Morning America — all for free.

(And now, with this report, NPR is biting on that lure: You can watch the video in our player here.)

Warner estimates it would cost between $100,000 and $200,000 to buy 30 seconds of commercial time on one of the big network morning shows.

"Stealth ads are very cheap to execute because you generally don't have to buy expensive media time," says Warren Berger, author of the books Advertising Today and Hoopla. He believes we will absolutely see a lot more stealth and viral advertising during the recession.

"We're in an environment now where viral messages can be very effective," Berger says.

But there's a lot of risk to go with the potential rewards of viral advertising. There's no guarantee a quirky video will get passed around the web.

That's why Eric Hirshberg of the agency Deutsch LA thinks we will see less of what he calls advertising-world "party tricks." Companies are cautious in hard times, he argues.

"There's an intensity and immediacy to their need to sell," Hirshberg says — though he himself often counsels against that corporate caution.

Now more than ever, Hirshberg says, people need to be charmed. And creative viral advertising can do that.

转NPR