[the-rc]

On one hand: just two formats? There are more, e.g. H264. And there can be multiple resolutions. On the same hand: there might be or might have been contractual obligations to always deliver certain resolutions in certain formats.

On the other hand: there might be a lot of videos with ridiculously low view counts.

On the third hand: remember that YouTube had to come up with their own transcoding chips. As they say, it's complicated.

Source: a decade ago, I knew the answer to your question and helped the people in charge of the storage bring costs down. (I found out just the other day that one of them, R.L., died this February... RIP)

[drewtato]

For resolutions over 1080, it's only VP9 (and I guess AV1 for some videos), at least from the user perspective. 1080 and lower have H264, though. And I don't think the resolutions below 1080 are enough to matter for the estimate. They should affect it by less than 2x.

The lots of videos with low view counts are accounted for by the article. It sounds like the only ones not included are private videos, which are probably not that numerous.