Some from the first PHAT PlayStation 2 Modells (SCPH−300xx Version 3/4) can if I remember correct play ESR patched Backups.
You can launch the ESR Patcher from the Memory Card (for that you need a modded PlayStation 2 to copy the ESR Patcher File as "boot.elf" into Folder BOOT on the Memory Card via ULaunchELF) and use the DEV1 Mode/Option (holding R1 on the Controller when powering on the PlayStation 2).
If you mean can you play movies burnt onto DVD-Rs, you should be able to without much of a problem. YMMV based on the quality of the disc your movie is burned on and the speed at which it's burned at, much like with any other DVD player. @alexander1970 answer up there is referring to game backups.
@Bunjolio, I don't really think your sister should be doing those things at a young age. No offense, but its likely possible that she got manipulated online?