“Investigation: How TikTok's Algorithm Figures Out Your Deepest Desires”
13 minutes video by the Wall Street Journal who did automated experiments to figure out how the algorithm worked and some of the consquences.

https://www.wsj.com/video/series/inside-tiktoks-highly-secretive-algorithm/investigation-how-tiktok-algorithm-figures-out-your-deepest-desires/6C0C2040-FF25-4827-8528-2BD6612E3796