I GOT MY Z1 INSTALLED A WEEK AGO AND THE INSTALLER DID THE PARKING BRAKE THING. BUT IT SEEMS THAT THE ONLY WAY I CAN WATCH MOVIES WHILE DRIVING IS WHEN I PRESS THE RESET BUTTON BEFORE I TURN ON THE CAR. BUT ONCE THE PARKING BRAKE WARNING COMES ON THE MOVIE DOES NOT SHOW ANYMORE. CAN ANYONE HELP ME?

If all your installer did was ground the parking brake wire, then it will not work.

Look in the Z1 hacks and mods section, there are umpteen posts on bypassing the Z1.

what does the installer have to do?

Look in the Z1 hacks/mods section.

Its 3 clicks away. Go find it.