Comment 7 for bug 123118

out of flashplayer, totem, vlc, java, only flashplayer was available by default ***but*** that's only because it is in my user ~/.mozilla/plugins, unlike the others.

By default, /usr/lib/firefox-granparadiso/plugins only contained libunixprintplugin.so (which does not appear in about:plugins).
So what I did was create the links already in /usr/lib/firefox/plugins. It fixed my problem. It's 100% reproducible and makes perfect sense to me as they use different plugin directories.