Echoing what others have already said... The movies you already have downloaded are there for you and your parents to use. Now, it's a matter of how you transfer and watch the pirated content.

Instead of manually throwing it onto a USB drive and having to delete, upload and wait for file transfer each time you want to switch the movies out, plex acts as a private portal to access your personal media library that exists only on your computer. No external party will be able to access or view what is in this portal.

Plex only cares about very large servers that break ToS (providing paid services to thousands of people). Even in that instance, plex only bans the account. No one cares if it's a small personal server. It's not worth the time, energy, or money to "swat" you.