I have seen on here that i am not theonly one who struggled to make vo work on linux with twinview. I can run it in windowed mode now, but i was wondering: is there a way to make it fullscreen on only one monitor?

I think it used to be possible to get that to work by fiddling with metamodes. You'd have to define a mode where one screen is disabled. It's explained in their readme:
http://us.download.nvidia.com/XFree86/Linux-x86/195.36.15/README/configtwinview.html
A lot of people said that it doesn't work anymore though maybe you'll have more luck.

An alternative might be to start a second X session for the game.

If you use KDE or another WM with the same function, do this:

- Run VO in windowed mode on desired screen.
- Set VO to match the resolution of the screen.
- Set the window Always on top (right click on the window title bar)
- Set the window Fullscreen (right click on the window title bar)
- Next time save these settings :)

Works perfectly except VO often steals mouse pointer. For example after jumping. Problem reported, no fix yet.