Comment 82 for bug 41335

@Diane: Do you have any idea about what exactly is not working? Do some movies work correctly?

If you are trying to watch a film protected by a regional code, it will not work out of the box. There are approximately two solutions to that problem.

1) install package libdvdcss2 from Medibuntu ( see http://www.medibuntu.org/ ). It does not cost anything, but may be legally questionable under some countries, which is why the package is not already part of your current Ubuntu installation.

2) buy a dvd player product for your Ubuntu from Fluendo ( see http://www.fluendo.com/ ).

In case you go with option 1, this bug thread may still be relevant to you. However, please, note that dvd playback has improved slightly with the latest version of Ubuntu. So in case you are using a version older than 9.04 upgrading to the latest edition may help a bit.