http://www.newsweek.com/youtube-anti-vaxxer-videos-conspiracy-theory-vaccines-alt-right-pipeline-1384042

YouTube executives repeatedly declined proposals to curb the proliferation of conspiracy, propaganda and other toxic video content over a period of years, according to a new investigation of YouTube by Bloomberg’s Mark Bergen. Rather than confront algorithmic recommendations pushing extreme right-wing and conspiracy theory videos, YouTube told employees not to look for questionable videos, in order to maintain plausible deniability regarding editorial oversight.

Beginning in 2012, YouTube began focusing on engagement, setting an ambitious goal of one billion hours of video viewing daily. The recommendation engine was rewritten to drive toward this goal, nudging viewers toward additional content by recommending new content at the end of every video. YouTube hit its billion hours viewing goal by October of 2016.