Hi Serge. It may actually be a problem specific to the patched xserver (I used Fanoush's deb) - I'm not able to reproduce the problem with the stock xserver. When running mplayer from the command line with the patched xserver (extra detail - I had sudo'd to root) the screen will blank - my settings are 2 and 5 minutes, LED enabled, Lock screen & keys not checked, default brightness 7 bars. When running mplayer via the GUI app the screen doesn't dim/blank - it's only a problem when using the command line. Nothing special on the command line - just "mplayer -benchmark -quiet <filename>".