The YouTube alt-right pipeline is well documented.
ACM study: https://dl.acm.org/doi/pdf/10.1145/3351095.3372879
MIT Technology Review summary of the study: https://www.technologyreview.com/2020/01/29/276000/a-study-o...
NYTimes feature: https://www.nytimes.com/interactive/2019/06/08/technology/yo...