Facebook CEO Mark Zuckerberg speaks at Facebook's corporate headquarters during a media event in Menlo Park, California, on June 20, 2013. Facebook announced Thursday that it will add smartphone video-sharing to its Instagram photo-based social network, in a move that challenges Twitter's popular Vine service. Instagram video apps tailored for iPhones and smartphones powered by Google-backed Android software feature 13 filters for special effects and post to people's Facebook pages the same way pictures do. AFP PHOTO Josh Edelson