Things were different between kids and music videos in 1998. That was the year that high-gloss videos captured Brandy and Monica fighting over a boy, Britney shimmying in a high school hallway, and 'N Sync lock-stepping in coordinated denim ensembles. Kids were ready to weigh in on what they thought of it all, and MTV delivered with Total Request Live, a show that let viewers vote on the videos they wanted to see, and even cut live to a viewer in the studio for instant feedback on the song. The audience soared to 1 million viewers, huge for an afternoon cable show; the coveted 18 to 34 demographic couldn't get enough.

And neither could advertisers. "Blocks of music videos were the first source of alternative programming," says Carrie Drinkwater, senior vice president of broadcast at ad-buying firm MPG. "It was the first youth-targeted genre and completely different from anything out there—which is what most brands want." Programs like T.R.L. created an everybody-wins juggernaut—the videos helped record companies promote their artists and helped MTV draw viewers, and, in turn, ad dollars.

Now, 10 years later, T.R.L. is going off the air; this Sunday, there will be a three-hour send-off special. It was once MTV's hallmark program and the go-to destination for video viewing. So what happened?

Culprit No. 1 is—surprise—the internet. If video killed the radio star, technology killed the video star—or at least the viewers' urge to wait to watch them on TV. Sony BMG now streams videos from its artists on a site called myplay.com. AOL and Yahoo both host music videos, as does, of course, YouTube. The video for "With You," a single from teenybopper favorite Chris Brown, has garnered 75.5 million views since it was posted on YouTube in December 2007. As the Washington Post pointed out in its coverage of T.R.L.'s demise, the ease of internet viewing made T.R.L.'s voting component, in which viewers dialed in for their favorite videos, hoping to see them make the top 10, look like a hassle: "Why waste time voting again and again for your faves? Why not just watch [them] 57 times in a row online?" wrote Monica Hesse.

MTV is trying to answer that question. As T.R.L. fades to black, the network is launching mtvmusic.com, its own branded all-video portal. Between the MTV flagship website and this new endeavor, the network will have more than 16,000 videos available for online viewing. "We've never had more music available for the viewers than we do today," says an MTV spokeswoman. "[But] we saw that there was no longer a need for a daily countdown of the top 10 videos."

As T.R.L.'s ratings plummeted, the audiences for MTV's traditional programming—reality especially—grew rapidly. Drinkwater remembers the 1992 premiere of The Real World as the first shot at the music video's preeminence on the channel. "As soon as you saw Real World getting some play, the reality just started coming and coming, and the uniqueness of video went away," she says. "The money is following the younger audience, and they want The Hills. They want to be voyeurs."

As T.R.L. disappears and reality quickly conquers MTV's slate, how the music video fits into the network's long-term strategy isn't altogether clear. "There are people who just like watching videos," says Drinkwater, who is hopeful for the mtvmusic.com venture, which, interestingly, features videos from the likes of Frankie Goes to Hollywood and riffs on the original network tagline, "I Want My MTV." "It's certainly an older audience, but I think there will be some way to monetize it."

To Tom McGrath, executive editor of Philadelphia magazine and author of MTV: The Making of a Revolution, the future looks a bit more grim.

"It's hard for me to imagine a scenario where the music video regains its pop culture cachet," he says. "To the extent that they help sell records and promote artists, I can see them continuing to exist. But it's also possible that they don't make sense anymore. They might be as obsolete as 45 RPM records."