We like to watch people trying to be famous. And we're so desperate for a shred of authenticity that we'll watch just about anyone doing anything, as long as it's live and on the Internet. Hence the lifecasting phenomenon.

Lifecasting's the extreme sport of oversharing. With cheap webcams and broadband available, it was only logical that the attention-seekers among us — most people under the age of 30, in other words — would start broadcasting themselves online, 24/7. It's not for everyone — Julia Allison, the New York dating columnist, claims to lifecast, but her sporadic videos don't even come close to the full-time lifecaster's output.

What's less explicable is why anyone, on either side of the camera, thought they could make money off the practice. A cottage industry of startups — Ustream.tv, Justin.tv, Kyte, Mogulus, and so on — sprang up around the naive belief that where there's a screen, there's an audience to sell. Even Yahoo got into the business. The hype fueled lifecasters' dreams of becoming famous and website operators' hopes to profit off their fantasies. Some lifecasters — like Justine Ezarik, also known as iJustine — even thought they'd parlay online notoriety into a business of their own selling product placements in their so-called lives.

None of that panned out. Advertisers only value authenticity when it's carefully scripted; the actual surprise of live broadcasts — violence, profanity, and sheer weirdness — is not a value proposition for them. And while lifecasting services have signed up millions of users, most attract an audience that numbers in the tens. No surprise, then, that Yahoo Live, the fading Internet giant's try at the market, is shutting down today.

A farewell video made by a Yahoo Live user, with clips cobbled together from various feeds, shows the problem. It's nearly impossible to police live broadcasts, leaving sites vulnerable to outbreaks of sex and nudity — or worse. And some will pay any price for fame. One Justin.tv lifecaster overdosed on camera last month — and some of his viewers laughed cruelly as he died.

If site operators do manage to keep things clean, users feel nannied to death — and are left boring each other silly. The most common activity on Yahoo Live? Spinning around in one's desk chair, over and over. Here's the best illustration — only slightly NSFW — of why lifecasting will persist as a mind-numbing timewaster long after it proves not to be a path to glory: