Brad Hunstable started Ustream, an online video platform, with a fellow West Point graduate back in 2007 to help American troops overseas communicate with multiple friends and family members at the same time. It was not long before its uses extended well beyond the military.

Celebrities, politicians and organizers of events like rock concerts and high school football games soon discovered that streaming services offered by Ustream and the other leading start-up provider, Livestream, could help expand their audience online. Now, the huge amount of user-generated live video produced by the Occupy Wall Street movement has delivered what could be a watershed moment for these companies, potentially helping them gain the audience needed to become viable businesses.

With cellphones, iPads and video cameras affixed to laptops, Occupy participants showed that almost anyone could broadcast live news online. In addition, they could help build an audience for their video by inviting people to talk about what they were seeing.

“It is a very immersive, interactive experience,” Mr. Hunstable said. “Something is changing when a person with a cellphone video camera can command an audience around the world.”

Max Haot, the chief executive and a co-founder of Livestream, recalls getting the cold shoulder when he was pursuing investors three years ago. Some of them flatly dismissed the idea of live streaming, he said, telling him online users preferred to watch video on their schedule, not at appointed times.

“The point that everyone missed was that people are not watching live streaming the way they watch a four-minute video on YouTube,” said Mr. Haot, whose New York-based company now has about 120 employees around the world. “They are watching so that they can be there and connect with an event.”

A live chat window runs alongside the video player on both Livestream and Ustream, giving users an opportunity not only to watch events as they unfold but comment on them, too. Since the first Occupy protest in Lower Manhattan last September, people from all over the globe have jumped into the conversation.

As a result, traffic to the sites has soared, and so has the amount of time spent viewing videos. For example, viewing time in the United States on Livestream totaled 411 million minutes in October, up from 270 million minutes in July, according to Dan Piech, product manager for video and social media at comScore, the analytics measuring firm.

Ustream is now also used by big brands like MTV and CBS News, which turned to its Ustream channel last Thursday to stream live video about the Virginia Tech shooting from its local CBS television affiliate.

On Ustream, Mr. Hunstable said, there are now about 700 Occupy-related channels, with 70 percent of the live streaming content created on mobile phones and about 89 percent of it viewed on mobile phones. Traffic to the site has increased by 14 percent since the movement began producing content.

The number of Occupy channels on Livestream is now about 120. Among them is the Globalrevolution.tv channel. It operates out of a makeshift television studio in the Bushwick section of Brooklyn and is considered the main channel for the movement.

Vlad Teichberg, 39, a former derivatives trader on Wall Street, is among the volunteers who aggregates live streams from the movement’s activities around the world. He first started live streaming from the protests in Madrid last May and then began using the technology to stream live video from Zuccotti Park in Lower Manhattan and from various other protest sites. “We will cover what the mainstream media will not cover and then propagate it using social media,” he said.

This week the channel delivered live coverage from several Occupy-related events around the country, including a march in Washington and a campaign to fight foreclosures in Los Angeles and New York. In Boston, Occupy organizers positioned 15 smartphones to help deliver live video from their tent city as a way for people to closely monitor the police who have been trying to move the protesters.

Both Livestream and Ustream officials say they simply operate platforms and are not supporting the movements. They have made some adjustments on their platforms and provided some extra resources to accommodate Occupy movement video.

Mr. Haot removed advertising from the Occupy channels after some brands complained that they did not want their ads appearing next to streaming video of protesters. Ustream lent more sophisticated video equipment to two citizen journalists, Tim Pool in New York and Spencer Mills in Oakland, Calif., after they consistently delivered high-quality streams. Neither of them is a trained journalist or highly skilled videographer, but they each managed to quickly build highly engaged audiences. Mr. Pool’s channel has had more than 874,000 views since September and has had as many as 28,000 live viewers at a time.

Despite increased volume and popularity, live streaming services face considerable challenges before becoming highly successful enterprises, analysts say.

“No question that what has been taking place in the world has done quite a bit to propel the adoption of services on platforms like Ustream and Livestream,” said Dan Rayburn, principal analyst for Frost & Sullivan and executive vice president of StreamingMedia.com. “But from an investor’s standpoint, there are a lot of questions to be asked.”

Mr. Rayburn said that one of the most important questions for live streaming services was whether they would be able to take their platforms to the next level and manage costs in an ever-changing landscape that includes YouTube, which has not yet fully embraced live streaming. “Can they scale the business fast enough while reducing their internal costs so they can make money?” he asked.

Mr. Haot said he expected that revenue for Livestream would be about $25 million in 2012, double the amount generated this year. Mr. Hunstable predicted that Ustream’s revenue, which he described as being under $20 million this year, would also double in 2012. Both sites derive the bulk of their revenue from advertising. They also offer premium channels without advertising for monthly fees and full production services if a brand or an event organizer wants a skilled team to stream an event or a red-carpet premiere.

Livestream and Ustream both said that they were looking at adding new features in the coming weeks aimed at increasing traffic, content and revenue. But they also said they recognized that competition could come anytime from new start-ups or from YouTube, which has an average of 161 million views monthly in the United States, according to comScore. In April, YouTube made video live streaming available to a limited number of participants in its partners program.

“YouTube is the behemoth in the space,” said Mr. Piech, the product manager for comScore. “No one else comes close to YouTube’s audience. If YouTube wanted to open a live streaming service, they could gain a significantly larger audience.”