Most of what people watch on YouTube is recommended by YouTube’s algorithm. Finish one video on how to save a dying houseplant, and it might suggest more. But that system can also send users down rabbit holes that radicalize and misinform. For almost a year, the Mozilla Foundation has been tracking the viewing habits of more than 37,000 volunteers who installed a browser extension letting them identify videos they called “regrettable.” Mozilla found YouTube’s algorithm recommended 70% of those problematic videos. Marketplace’s Kimberly Adams speaks to Brandi Geurkink, senior manager of advocacy at Mozilla, who led the research effort.