How to achieve a certain backdrop effect

As shown in the video, how would one go about achieving the effect of the moving squares on the floor and ceiling? I don’t see how it would be done using a skybox and instantiating those squares individually would take up too much processing power, wouldn’t it? Any help appreciated, thanks!

I would just use two particle systems. Change the Shape to box and make it very small on the Y axis. Then have a start speed, and constant velocity on negative Z.

Thanks, I’ll try that out and hopefully it works out well!

It might even be two big planes with textures on them.