Apple says the VP9 codec no longer works on Catalina. I want this codec for my older OS. Where can I find it?
Welp, I'm still not sure whether there ever was a VP9 component, but there is now because I made one. I managed to update FFusion (the core component of Perian) to work with a newer version of libavcodec.
https://github.com/Wowfunhappy/FFusion
At long last, I can watch 4K Youtube videos in QuickTime Player 10.2.