Excellent Howto!
There's one thing I'd like to add. If you have a 16:9 screen and want to start elisa @ 800x600 but keep normal sessions and gdm at a higher resolution you can add a xrandr to the ~/.xprofile of your elisa user. As you mentioned, adding the physical dimensions of your screen to xorg.conf allows elisa to correct the aspect ratio of movies. But xrandr resets this information. There is an parameter for xrandr to tell which dimensions to use:
Hint for xrandr: changing the resolution and keep aspect ratio
Excellent Howto!
There's one thing I'd like to add. If you have a 16:9 screen and want to start elisa @ 800x600 but keep normal sessions and gdm at a higher resolution you can add a xrandr to the ~/.xprofile of your elisa user. As you mentioned, adding the physical dimensions of your screen to xorg.conf allows elisa to correct the aspect ratio of movies. But xrandr resets this information. There is an parameter for xrandr to tell which dimensions to use:
xrandr --output VGA --mode 800x600 --fbmm 340x190