Your company operates a global video sharing platform with millions of daily active users who both view and upload videos. The platform's success heavily relies on user engagement, which is significantly influenced by the visibility of popular videos. You are tasked with developing a machine learning model to predict which newly uploaded videos will become the most popular within the first 30 days after upload. The goal is to feature these videos prominently on the website to maximize user engagement and ad revenue. Given the platform's scale, the model must efficiently process thousands of videos daily, considering factors like video content, uploader history, and initial engagement metrics. Which of the following metrics should you use to evaluate the success of your model, ensuring it aligns with the business objective of maximizing watch time and user engagement? (Choose one correct option)