Financial terms were not disclosed. As part of the deal, Sandy MacIntyre, AP's director of global video news, will join Bambuser's board as a director.
The deal caps a three-year relationship between the news agency and Bambuser. Last year, the AP signed a deal with Bambuser giving the agency exclusive syndication rights to user-generated content video posted on the service, meaning that if users want to share their video with a news agency, they do it only with the AP, MacIntyre said.
"This investment by the AP is a natural extension of our existing relationship with Bambuser and will ensure that we retain our dominant capability in gathering and verifying UGC video news," he said in a statement.
Bambuser, which was founded in 2007 in Stockholm, allows users to broadcast, watch and share live video through smartphones and computers. The AP said Bambuser's products are designed particularly to cater to the needs of the news industry.
The service is free for individuals and nonprofit groups. To broadcast live, users need to install an app on their smartphones or use a Web browser with Flash technology on regular computers. People can watch videos on Bambuser's website via computers and mobile devices.
Generally, neither AP nor Bambuser pays users to publish the content they post, MacIntyre said.
Access to user-generated content has become increasingly important for media companies like the AP, which has growing demand for live video from its broadcast and online customers.
"Working so closely with the AP over the last year has proven the huge demand for user-generated video content," said Hans Eriksson, executive chairman of Bambuser. "This equity investment is an important milestone in Bambuser's journey, as it not only brings our two organizations closer, but enables us to share our expertise to an even greater extent."
The AP said the deal with Bambuser gives it access to an established community of video contributors around the world. The service also is used by the news agency's own journalists in the field to send video to the AP.
The AP noted that it already uses verified user-generated content regularly, citing the civil war in Syria, the aftermath of the Boston Marathon bombings and recent storms in Oklahoma as examples of recent stories where such content played a role.
MacIntyre said that through its relationship with Bambuser over the past year, the AP has been able to access footage of breaking news it couldn't get any other way. He also noted that user-generated content is poised to grow in both importance and volume.
"Nearly a fifth of the world's population has a smartphone and that is a phenomenal eyewitness resource that Bambuser makes technologically possible," he said.