Okay kiddo, so there are some really old movies and videos that were created a really long time ago. These movies and video are called "public domain films".
Do you know what "public domain" means? It means that something is owned by everyone and nobody owns it. It is just out there for anyone to use or watch without having to pay money or getting permission from anyone.
So, public domain films are really old movies or videos that have been around so long that nobody owns it anymore. This means anyone can watch these movies for free and use them for different things because nobody owns the rights to them.
These public domain movies can sometimes be really old and might look different than the movies and videos you see today. But they are a really important part of history and it's great to be able to enjoy them without having to pay a lot of money or getting permission from anyone!