So, your Mac is set up, and you've decided to use DVD Player instead of Front Row. Good choice! But there are some settings that you should tweak for it to go as smoothly as possible. In the preferences window:

Set it to go to full screen when opened, and that it should start playing automatically.

Set your preferred settings for Audio and subtitle.

Set it to hide the control window when inactive after 1 second. It should also remain in fullscreen when inactive.

Set it to Last position played