This is not comparable to Netflix et al. YouTube catalog is effectively infinite, and people watch all kinds of random content. Storing 10k movies and 20k TV episodes is a cakewalk compared to this.

I don't disagree that YouTube has a much longer (and fatter) tail, but that doesn't mean they can't benefit from edge caching.

They can benefit for sure, my point is that serving a YouTube type catalog is just far more expensive.

There's undoubtably more data being served but I'd be very curious how the edge caching efficiencies differ given how many people watch the same things (recommended by the algorithm) and since YouTube's content is so much shorter on average that larger catalog is somewhat balanced by any given cache node being able to hold more videos.

The cache hit rate is actually pretty high. Also, google already has setups at pops for other reasons and can cache fill at lower qos for free much of the time.