On Wed, 3 Jun 2009 at 12:44pm, MHR wrote
"Erm, what?"
-stop-xscreensaver (X11 only) Turns off xscreensaver at startup and turns it on again on exit.
These are the only two appearances of the word "screensaver" on the man page. There is no reference to a heartbeat-cmd.... (CentOS 5.3)
What version of mplayer are you using (and from what repo)? The CentOS version doesn't help too much, as mplayer isn't included in any of the default repos. And this doesn't appear to be a very recent feature (googling reveals references to it that are over a year old).