The top four content categories watched by YouTube users are comedy, music, entertainment/pop culture, and "how to." Appears In The latest YouTube stats on when, where, and what people watch Related Data Mobile watch time of test drive videos on YouTube has grown by over 70% in the past two years. Black millennials' mobile watch time on YouTube has more than doubled in the last two years. 81% of video-viewing occasions get all or most of people’s attention. In the past two years, videos with the word "review" in the title had more than 50,000 years worth of watch time on mobile alone. In the past two years, watch time of “shop with me” videos has grown over 10X on mobile alone. In the past two years on YouTube, videos with "review" in the title had more than 50,000 years' worth of watch time on mobile alone.