Fedora 30 - Fix YouTube not playing HTML5 videos.
After a clean install of Fedora 30 KDE Spin, youtube cannot play html5 content.
The fix is quite easy:
sudo dnf install https://download1.rpmfusion.org/free/fedora/rpmfusion-free-release-$(rpm -E %fedora).noarch.rpm https://download1.rpmfusion.org/nonfree/fedora/rpmfusion-nonfree-release-$(rpm -E %fedora).noarch.rpm
sudo dnf install ffmpeg-libs
Restart firefox and it all should work again.
Easy fix but I always forget about it.