The new live streaming platform will be previewed in a two-day trial beginning Monday, but is expected to later grow considerably across the Google Inc.-owned website.
Four YouTube partners will participate: the celebrity-focused Young Hollywood; the online television outlet Next New Networks; the how-to guide Howcast; and Rocketboom, the Internet culture vlog.
"This is just an initial trial, a first step," said YouTube product manager Josh Siegel. "We're going to look at a whole bunch of data about the performance of our new platform and then, based on that, make decisions about how we'll open it up, with the goal of opening it up to all of our partners over time."
For the last two years, YouTube has offered numerous events live, including a U2 concert, cricket matches in India and President Barack Obama's first State of the Union address. But for all of those events, YouTube relied on third-party technology to enable the live webcasts.
Chris Hamilton, a product marketing manager at YouTube, said live streaming is "a natural evolution to online video" that "adds an extra level of engagement" for the site's audience.
YouTube, though, is far from the first company to step into the streaming video space. Startups such as Ustream.tv, Justin.tv and Livestream have already established themselves.
But YouTube remains the largest video platform on the Web and is expected to quickly become a considerable force in the rapidly growing live streaming video business.
ComScore recently announced the amount of time American audiences spent watching the major live video publishers grew by 648 percent in the last year. The advertising possibilities are also good, since the average live streamed video view is 7 percent longer than the average online video view, according to ComScore.
Ustream is the current leader in live video, with 3.2 million unique viewers in July. But Google video sites, which are primarily driven by YouTube, drew 143.2 million unique visitors in July, according to ComScore.
Hamilton said YouTube will be monitoring the live trial to see how well the video looks and how well servers handle any bandwidth increases.
Among the broadcasts scheduled for Monday beginning 11 a.m. EDT is Rocketboom, which is planning an hour-long variety show, pulling from Rocketboom and its numerous spin-offs. Producer Leah D'Emilio said the site is planning a TV-like broadcast, with multiple cameras and correspondents.
She expects that live streaming will further engage the YouTube community.
"Any time you can bring your viewers into a broadcast -- like making a shout-out to someone who left a comment -- the audience really gets excited about that, on YouTube in particular," said D'Emilio. "It breaks down any kind of wall between the people on camera and the people who are watching."