Comment 6 for bug 173517

huiii, have you tried modifying the /usr/bin/compiz to include the --only-current-screen in the list of default parameters to be given to compiz?

This is what I use now and at list I have compiz working fine on the first screen, and on the second I can watch full screen videos (after making them fullscreen with the mouse, I can use the keyboard - to pause, for example. Sometimes the keyboard doesn't work in fullscreen either, but a quick switch with the mouse from the fullscreen into window mode and back seems to re-make the keyboard work :) ).
This is how it look the line modified in /usr/bin/compiz:

* before: COMPIZ_OPTIONS="--ignore-desktop-hints --replace"
* after: COMPIZ_OPTIONS="--ignore-desktop-hints --replace --only-current-screen"