BuddyPress.org

Well, personally I’d use VideoPress if I wanted to host my own videos/images. If I didn’t want to do that I’d probably write a YouTube/Vimeo/Flickr plugin.

Not a big fan of Kaltura. I tried it when I was toying with the idea of using Elgg, but back then it was clunky and unintuitive. Might have changed, though. That was about a year ago…