The link is created in a wrong place. Your setup is still working because the link is still there, but take a look at /var/lib/dpkg/info/mozilla-plugin-vlc.list
As said there, thje link is created on /usr/lib/mozilla-firefox/plugins/libvlcplugin.so that it's the wrong place again.
The link is created in a wrong place. Your setup is still working because the link is still there, but take a look at /var/lib/ dpkg/info/ mozilla- plugin- vlc.list
As said there, thje link is created on /usr/lib/ mozilla- firefox/ plugins/ libvlcplugin. so that it's the wrong place again.