We set up Falcon Pi Player on two Raspberry Pis to be master & remote video players on a WIFI network. The master will help keep the remote in sync so they videos play together with very little drift.
Setting up a Raspberry Pi as a media player using Falcon Pi Player (watch this introductory video first if you aren't familiar with Falcon Pi Player or how to make them into a media player): https://youtu.be/YYYllsv_dQw
Equipment Used (Amazon affiliate links):
Raspberry Pi 3 B+: https://amzn.to/3HvMiii
Raspberry Pi 4 (4 Gig Model): https://amzn.to/3qRwhxc