I've run into this too, sometimes I want to suspend/sleep the monitor RIGHT now.
So what I did was make some shell aliases to call the xset commands to do it
from a terminal window:
alias dpmsoff "xset -dpms"
alias dpmson "xset +dpms"
alias off "xset dpms force off"
alias standby "xset dpms force standby"
alias suspend "xset dpms force suspend"
(see the man page for xset for much more detail on those)
these are "T shell" aliases in my ~/.tcshrc file. I tend to use the last two
more often, they just force the monitor to suspend or standby but
leave the general dpms state alone.
Most Fedora users use bash shell which I don't like, but bash has similar alias support.
But basically xset -dpms is a very quick way to turn off dpms entirely. You can then watch your movie
and know it won't go to sleep. When you're done do ... :
If you want to be a bit slicker, you can change the KDE command that's passed to
Linux when you launch your movie program via KDE's menu so that it calls the xset -dpms
call, then the movie program, then the xset +dpms. This way as long as you're starting the movie program from the
KDE start menu, you won't have to
remember to go back to dpms ON mode when the movie is done
(or forget to quit dpms when you start)
You'd do this by using the KDE Menu editor, then in the 'command' slot
for the movie program (say "totem") change this (see attached pic):
xset -dpms; totem %U; xset +dpms
(NOTE the semi colons must be there to separate commands logically)
I've tried this and it works. I confirmed it by starting totem after making that change and , then in a terminal
I ran "xset -q" to query the Xorg settings, those showed dpms was disabled, then immediately on
quiting Totem, the dpms was back enabled again.