tor-browser can't see ffmpeg

[onatinadresi]

before installing ffmpeg, both tor-browser and firefox-esr play
youtube videos with sound. after installing ffmpeg, firefox-esr
plays videos on other sites too but tor-browser does not. it
shows a warning that I need to install codecs. I wonder if it's
an unveil issue. I would try disabling unveil for tor-browser
but I couldn't find any documentation on how to disable unveil