The streamer's name is James Varga, and according to reports, the games he was broadcasting were shut down by hackers performing distributed denial of service attacks. These games included League of Legends, Dota 2, and those through Battle.net. Varga continued to communicate with DERP during this time, and either DERP or a third party escalated matters by calling 911 and claiming that Varga was holding hostages in his home. Varga was then briefly detained while the police searched his home, but he was released without charges.
This is similar to an incident earlier last month when a World of Warcraft livestreamer was arrested after someone called the police on him to interrupt his stream.