SAN FRANCISCO -- Flickr on Thursday began rolling out "radically overhauled" mobile video-sharing features that make the popular website more social and easier to use on the move.

A revamped m.flickr.com is initially available to users of Apple iPhone and iPod Touch handsets but will be quickly expanded to "smartphones" equipped with Opera or Firefox mobile browsers for surfing the Internet.

Flickr mobile is being adapted for Nokia N series mobile telephones as well as "Google phones" based on the open-source Android operating platform backed by the Internet search powerhouse.

"More and more of our members are coming to Flickr on mobile devices, and this is a recognition of that change," Flickr senior product manager Shanan Delp said while discussing the changes at the Yahoo-owned website.

The number of visits to Flickr by people using mobile devices jumped 50 percent in the past year and Delp expects that trend to accelerate.

Early this year, Flickr began letting users with "Pro" accounts upload videos to the globally popular photo-sharing website.

The Flickr mobile overhaul lets those members, who pay a $25 fee to upgrade from free accounts, upload or download videos from smart phones and exchange text comments with people they allow to view the snippets.

"We've also added a bunch of new capabilities, like letting you add contacts, favorite images, and change your privacy and permission settings all while you're out walking the dog," Flickr general manager Kakul Srivastava said in a blog posting.

Any Flickr user can watch videos at the website provided that whoever uploaded the material grants them access.

Yahoo Video technology was put to work at Flickr to allow "progressive downloading" of video files to mobile devices as opposed to real-time streaming that doesn't require digitized data to be stored in handsets.

"We think that is the emerging standard as best way to deliver these files to phones or computers," Delp said of progressive downloads of video.

Flickr mobile features a main page with tabs that let users easily check image updates and feedback from friends, as well enabling them to do most of the things they could if they were visiting the website from desktop computers.

"We want our members to think of this as an infinite feedback loop where they take pictures, share them with friends instantly and hear back immediately," Delp said.

"It is almost like lifecasting -- sharing whatever you see in the world instantaneously."