>I suspect YouTube would predict the popularity of videos and only cache where it matters (low anticipated popularity videos would be pushed to CDN if they perf

>I suspect YouTube would predict the popularity of videos and only cache where it matters (low anticipated popularity videos would be pushed to CDN if they performed better than expected). That's actually a really interesting point, because YouTube can (partly) decide which video will become popular. They control what shows up as a suggested video, what appears at the top of search, what shows up in the subscription feed (unless the subscriber has clicked the bell icon).