But that’s like the whole point of docker compose. If you are just going to have 1 container per file what benefit are you even getting out of using a compose file?

No, you can do more than 1 VLAN per port. It’s called a trunk

I could see it being a lot more useful for Japanese or other no Latin alphabet languages. Especially for the kanji. I’m too early in Japanese to watch content.

I don’t think I count as a polyglot (Native English, Spanish proficient, learning Japanese and German) but what is that even useful for? I feel like it’d be really confusing to have two subtitles for the same dialogue.

I just watch, in whatever language I want to practice.

Very likely that you use web apps regularly. It’s very commonplace.