Questionable if this is only about movies, and not about any Bittorrent traffic.
The Great Firewall can’t block torrenting, especially not within the country itself. It’s a decentralised protocol though, so trying to block every non-chinese seeder without blocking the wider internet itself would be just a game of whack-a-mole. I also don’t think it’s as simple as just English audio, but English sites. Russia absolutely has a bunch of super specific .ru sites for torrenting. Generally the best place to find patches for pirated video games. I could imagine it might be similar for the Chinese scene.
As well, even for English audio stuff, I bet they’d get reuploaded with subtitles added a lot to sites in places like Russia.