In February, YouTube announced it had hit a staggering milestone: visitors were now consuming the equivalent of a billion hours' worth of video every day. Some of YouTube's most popular channels are aimed at children, with creators ... gaining millions of subscribers and billions of views. But there is a problem. YouTube is absolutely flooded with extremely violent, inappropriate, sexually suggestive videos targeted at children. These videos are finding their way into autoplay lists alongside age-appropriate clips. Journalist James Bridle delved into this unsettling phenomenon, dubbed Elsagate. He found that as content creators chase viewers, successful - and originally harmless - formulas for garnering views are "endlessly repeated across the network in increasingly outlandish and distorted recombinations". At their most extreme, these include a legion of unsettling videos which appear to be produced, or in some cases automatically generated, in response to popular keywords. They often feature disturbing themes and sexual or violent content. For instance, a search for "Peppa Pig dentist" returns a homemade clip in which the popular children's character is "tortured, before turning into a series of Iron Man robots and performing the Learn Colours dance". ElsaGate has exposed a long-standing truth about YouTube that can no longer be ignored, says Polygon: the filters designed to protect users of all ages from disturbing, violent or illegal content are not up to the job.