When Brenton Tarrant, a 28-year-old Australian man, turned on the camera on his mobile phone and filmed himself and his actions during a murderous attack on two mosques in Christchurch, New Zealand, killing 50 people, it brought home to the world that the idea of web-casting, so beloved of American TV cop-show writers, can be even more horrifying when fiction turns to fact. Yet, the dangers of live streaming have long been known and criminals in a wide range of activities have been making use of it for a long time. Is this a "freedom" too far?