An article that shows how Youtube processes user-submitted videos to publish them online.
https://www.cnet.com/news/google-supercharges-youtube-with-a-custom-video-chip/
That sure seems weird.
I did lots of tests with webm (vp8 and vp9). It is a pretty good thing. Especially when you like the idea of Open Source. There have been lots licensing problems with MPEG. Maybe you remember. I don't know how free and open it really is or will be in the future but I prefer to make the basic stuff available for future development and public usage.
VP8 and VP9 (it is AV1 right?) of course can create smaller video sizes but in my tests they have always been worse than the original h264 file.
Sometimes it can make sense for self hosted clips to make a clip with a mobile friendly bitrate. Especially clips with lots of movement often need far more bitrate.
In the case of Youtube of course they need as little space as possible for the unpaid accounts. And the encode efforts must be enormous
500 hours of YouTube video uploaded every minute? Wow !!