Hi there @corinna212697 and welcome to the forum,
There’s definitely a few ways to go about doing that.
Do you know how you will be playing the video yet i.e. through a web browser or a program like VLC? Either way would slightly change the process of doing so (although not too much).
This tutorial for the Pi 4 shows how to make a video looper on the Pi 4.
Whereas this tutorial would show how to set up a Pi to boot automatically to a webpage, which would be very useful if you were playing a Youtube vid.
