It was a short movie that I saw in a movie theater before the main movie (can't remember the movie). I saw it in Belgium, but there was no intelligible dialogue in it. I think I saw this between 2000 and 2012.
It's basically an adaptation of 1984, with cabbages moving in stop-motion. They live in a white (or grey?) city, probably in paper. I clearly remember a little bridge.
All of the cabbages are red. There's a picture of the leader everywhere, and he gives speeches in a gibberish language. Every red cabbage seems to act like a soldier.
The hero is a green cabbage, who is clearly different and thinks differently. He's presented as a dreamer, I guess. He hides himself from the other military red cabbages. I think he also speaks to other cabbages in secret reunions, maybe to start a revolution.
The hero is finally captured by the red cabbages. I can't remember the process but he finally turns red too (like he was brainwashed). It's quite tragic.
The camera leaves the city but we have a last hope; another green cabbage can be seen moving on the screen, with the same music used to introduce the first green cabbage.