Possibly Twitch, Amazon Prime Video, and another one that escapes my mind (AWS-related?).
In the now deleted tweet Theo thrashed VLC codecs to which ffmpeg replied basically "send patches, but you wouldn't be able to". The reply to which was
--- start quote ---
https://x.com/theo/status/1952441894023389357
You clearly have no idea how much of my history was in ffmpeg. I built a ton of early twitch infra on top of yall.
--- end quote ---
This culminated in Theo offering a 20k bounty to ffmpeg if they remove the people running ffmpeg twitter account. Which prompted a lot of heated discussion.
So when Google Project Zero posted their bug... ffmpeg went understandably ballistic