NVidiaProprietaryDriver
Basically, everything you need to get this working you will find in their Readme file; read Appendix J which deals with TV-Out.
One common symptom is the following: the NVidia driver may (or may not) give one or more blue lines surrounding the actual TV or DVD playback. This is something which is mostly seen on widescreen TV displays. The following command solves the problem:
xvattr -a XV_COLORKEY -v 66048
Add the command somewhere in the Xorg startup sequence (need more distribution-specific information about how to do this.)
For users experiencing black-and-white TV output: please verify if the TVStandard option is set to the one valid for your country. All NVidia cards I have seen default to the American TVStandard 'NTSC'. For a mythtv box in the Netherlands use the following option in the Device section in xorg.conf:
Option "TVStandard" "PAL-B"
To get rid of that annoying NVidia logo at startup, also add:
Option "NoLogo" "True"
in xorg.conf.