I use Ubuntu 18.04 and Firefox 60.0 (linux beginner!)
I just installed the flash player, but the only videos that are displayed in my browser are the ones on youtube. facebook and any other streaming-services can not play videos.
do i need to install/enable html5 somehow?
If those streaming services use DRM, you must enable DRM in Firefox's settings: Preferences -> General -> Play DRM-controlled content You might also have to install package
libavcodec-extra
to get the codecs:sudo apt install libavcodec-extra