This post is for those who might want to use Linux in a virtual box as a region free DvD player in Windows.
Linux Mint MATE comes with media player named 'totem' installed.
Right out of the box, this media player appears to play DvD's from different regions, even though my DvD drive is set for region 2.
However, if I run Linux as a guest in a virtual box on a host Windows 8 system, then it says the disk is encrypted and that I need a decoder library.
Installing the package 'ubuntu-restricted-extras' (which includes the decrypter libraries), makes NO difference: it still won't play the DvD!
The strange thing is that the DvD it fails on IS region 2 (like my DvD player) but it is only playing DvD's of region 4 (where I live at the moment and bought my Windows 8 upgrade). This limitation to zone 4 is then both under the host OS (Windows8) and in the guest Linux Mint!
I suspect it is a 'feature' of the hosting Windows.