Man, I loved that line about how they could shut down three Amazon projects with a single email. That small bit of leverage against these parasites is all they have.

They couldn't just make YouTube suddenly stop working.

ffmpeg is published under the LGPL license, meaning that all of the published versions are free for anyone to use in anything, as long as they don't modify the ffmpeg library.

The only leverage they have over YouTube is that they could stop allowing YouTube to use future versions. That could create headaches for YouTube if it turns out there's major security issues, since then YouTube will need to either solve them with a wrapper / sandbox around the library, or write their own library, but any existing versions in use will always be usable by YouTube.