Social media's place in spreading mosque killing video

The role that the tech giants played in the proliferation of the chilling self-streamed footage of the alleged gunman Brenton Tarrant's attack has been a talking point. The mass killing was live streamed on Facebook, announced on 8chan commented about on Reddit. Is it time tech companies were really called to task? Andrew Cushen of InternetNZ says it's hard to know what to do next.