Comment 23 for bug 455073

The -stop-screensaver option may not work. According to the mplayer manpage, it's a problem of the screensavers:

       -stop-xscreensaver (X11 only)
              Turns off xscreensaver at startup and turns it on again on exit.
              If your screensaver supports neither the XSS nor XResetScreen-
              Saver API please use -heartbeat-cmd instead.

       -heartbeat-cmd
              Command that is executed every 30 seconds during playback via
              system() - i.e. using the shell.

              NOTE: MPlayer uses this command without any checking, it is your
              responsibility to ensure it does not cause security problems
              (e.g. make sure to use full paths if "." is in your path like on
              Windows). It also only works when playing video (i.e. not with
              -novideo but works with -vo null).

              This can be "misused" to disable screensavers that do not sup-
              port the proper X API (also see -stop-xscreensaver). If you
              think this is too complicated, ask the author of the screensaver
              program to support the proper X APIs.

IMO the ubuntu developers should try to fix the screensavers instead of trying to "fix" mplayer.