Estimate the number of videos watched on YouTube per day.

To estimate the number of videos watched daily on YouTube in the US, we can start with the US population (approximately 330 million). We'll exclude children under 5 and individuals over 80, as well as those without reliable internet access, which might reduce the potential user base by about 15-20% (roughly 50-65 million). This leaves us with around 265-280 million potential users. Assuming a daily active user penetration rate of 50-60% for a platform like YouTube, we arrive at approximately 130-170 million daily active users. If each user watches an average of 3-5 videos per day (considering a mix of short and long-form content), the total number of videos watched daily would be in the range of 390 million to 850 million.