Customize Pay Per View Plugin

I have a theme that loads videos directly from the database, not the post. I need to protect that content... I tried to follow the "customization Help" but am not a programmer, and ended up with a "500 Server Error" when I added the code to functions.php

The template code that needs to be protected is this:
<?php dp_video($post->ID, get_option('dp_single_video_autoplay')); ?>

I know it is a lot to ask, but could you tell me what code I need to add to protect the video please?