When Mans Adler founded Bambuser—a Sweden-based service that lets people broadcast live video from their cell phones to the Internet—his idea was simply to help users share their lives with friends in real time. Early this year, however, Adler saw an explosion of use from a political powder keg: Egypt.

During the Arab Spring, pro-democracy activists discovered that Bambuser let them thwart the Egyptian secret police. If a protester filmed an incident of police brutality, it didn’t matter whether they were arrested and their phone confiscated: The footage had already ...