There’s a very useful CLI program to change the region lock of a DVD drive, thus allowing people to read on their PC DVDs sold in a different area of the world from where they live: regionset.
The license is GPLv2 (not specified on their site but included in the downloadable source code archive). And I know this package is included in other FSDG-compliant distros like Trisquel or PureOS.

Possible caveat: the software is old (latest version is from end of 2012).