What is the name of this (possibly communist) movie?

I watched this video on youtube called The Greatest Speech Ever Made. It was a speech delivered by Charlie Chaplin and it was a montage of emotion-stirring scenes from various movies and tv shows. (not spamming, but here is the link: https://www.youtube.com/watch?v=WibmcsEGLKo)

One particular movie which captured my attention was one I believe is possibly some 1984-like movie. It shows scientists staring ahead and studying something while a projector beams behind them (0:52) and men mindlessly marching on a catwalk in a factory and falling (1:23). Machines move below them and their shadows cast a Communist symbol on the walls (2:07) and pink meat comes out of a meat grinder.

THE SCENE I SEARCH FOR THE MOST is one where it shows children taking off masks and jumping up and cheering. (2:47) at some school or gym.

Keep in mind, I only think those scenes are connected and part of the same movie because they are all gray and depressing. I have been searching for this movie for a long time now. Could anyone please tell me what it is?