Contributors to the popular video-sharing site YouTube can now find details about who is watching their videos and when.

Launched Thursday, YouTube Insight is a free program that breaks down how many times users start a video, viewership by day and the geographic locations of viewers, tracked using internet protocol addresses.

Some data will be limited to paid advertisers, the Associated Press reported, such as how many viewers make it through 25 per cent, 50 per cent or all of a video.

Until Insight, contributors could only get limited information on their videos from the site, such as how many times it had been viewed or commented on.

The new service "turns YouTube into one of the world's largest focus groups," said Tracy Chan, a YouTube product manager, in a blog entry announcing Insight.

Chan said posters can "also delve deeper into the lifecycle of your videos, like how long it takes for a video to become popular, and what happens to video views as popularity peaks."

'Inside look'

It "gives the creators an inside look into the viewing trends of their videos on YouTube, and helps them to increase views and become more popular," Chan added.

Chan said partners and advertisers will also find the tool useful, as they can use the data to tailor advertising on and off the site.

For example, a movie studio that uploads a trailer could see where the clip is most popular and buy ads targeted to users in that region. Or a band could see their ads are most popular on Wednesday, and start posting them at that time. Retailers could even see that their products are popular in another country and start translating their advertisements accordingly.

"With this information, you can concentrate on creating compelling new content that appeals to your target audiences and post these videos on days you know these viewers are on the site," the YouTube team said in a blog entry announcing the program.  

The YouTube blog entry also said they will "be making new features and additional information available fairly quickly."

Upcoming features may indicate how viewers find a video, for example, whether it's through a search, an outside link or the site's share-with-a-friend feature, Chan said.

With files from the Associated Press