Playing Facebook videos on Linux in Firefox, Chrome, etc.

[Obsolesce]

It took me a little bit of digging, and I got lucky finding an easy solution:

su -c 'dnf install http://download1.rpmfusion.org/free/fedora/rpmfusion-free-release-$(rpm -E %fedora).noarch.rpm http://download1.rpmfusion.org/nonfree/fedora/rpmfusion-nonfree-release-$(rpm -E %fedora).noarch.rpm'

dnf install ffmpeg-libs

If you go to https://youtube.com/html5, you'll notice that the middle two may be missing. The above fixes it.