I use Ubermix 2.1L for older computers that are refurbished and given to students. One of the problems that I encountered was that some students reported the system would not play commercial DVDs. After verifying it wasn't a DVD drive hardware problem, I determined that Ubuntu 14.04 really doesn't have the final step done to allow DVDs to play. Here's all that is required to get UM 2.1L starting and playing DVDs without problem.
1. From the desktop, use CTRL-ALT-T to get to the command line. Make sure you are connected to a network.
2. Type the following on the command line: sudo /usr/share/doc/libdvdread4/install-css.sh
3. After it finishes, close the terminal window. Put in a DVD. When it starts, you are asked to verify the application to use. I use the default (videos) and check the box to always use this application.
4. DVD will run as expected.
I would guess this should be done then apply simple updates so you won't need to do this on each installation. Maybe it can already be done in the next UM version?
