I'm guessing it would be the ubuntu-restricted-extras package (if any) .. though if I remember correctly Mint has support for the stuff the "extras" package adds by default.
If you can play flash, mp3's,and commercial DVD's by default you don't need the "extras"
ubuntu-restricted-extras is just a metapackage that pulls in some other packages as dependencies/recommends .. here's a list of the packages ubuntu-restricted-extras installs:-
ubunbtu-restricted-addons then pulls in:-gstreamer0.10-plugins-ugly
adobe-flashplugin | flashplugin-installer (either ONE of those, NOT both)
So if you already have the ones in bold
, you're not going to need the ubuntu-restricted-extras package.
Be aware the above info is for Ubuntu 13.04 .. the package versions might be slightly different in Mint 16 which is based on Ubuntu 13.10