Watch a 24-minute conference talk from Data Science Conference Europe 2023 exploring the complexities of YouTube's recommender systems for big screen users. Delve into three key challenges faced at YouTube's massive scale: understanding diverse user behaviors across platforms, strategically improving system performance through targeted investments, and balancing measurable success metrics with implementation costs. Learn how YouTube tackles the intricate task of delivering timely recommendations to billions of users through multiple machine learning and heuristic models. Gain insights into the specific approaches and solutions developed to address these challenges, particularly focusing on the big screen user experience.