I did recently try out the nvidia-settings tool which allows you to tweak the
settings and found a quite usefull setting "TV Flicker Filter", which has
improved the TV-out quality a lot.

I would like to set this by default for my X Windows System, but there aren't
any documented X option in the 6629 manual and I'm now wondering if there is
an undocumented option that can be used to set this?
I do know hot to set this by user, but I don't want that but system wide.