Ever watch something on YouTube and wished you hadn’t? You’re not alone.

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.