Power Management doesn't turn off screen when video is running but will run commands

I’ve been playing with the possibility of running a screensaver and it occurred to me that KDE doesn’t turn off the screen when I have games or videos running but xscreensaver would so I thought I’d use the KDE power management option ‘When inactive do X’ to invoke the screensaver instead of using xscreensaver’s own timer. Enter the problem: For some reason the “Display and Brightness” function to turn off the screen uses different inactivity criteria to the “Other Settings” script runner, is there anything I can do about this or is it a bug I should report?