The authors thank Guy Aridor and Wes Hartmann as well as seminar participants at Columbia Business School, the Economics of Digital Services Research Symposium, the Federal Trade Commission Conference on Marketing and Public Policy, Simon Business School, and the Workshop on the Economics of Advertising and Marketing for their helpful comments. The authors thank Zhengrong Gu, Zifan Huang, Kushi Kiran, Yuqing Yang, and Kradon Zhao for their research assistance. The authors thank Jason Urgo at Social Blade and the YouTube Researcher Program for providing data.