1. This movie is boring to young people.
2. This movie is boring for young people.
What's the difference in meaning between the above two sentences?
I need native speakers' help.
2. is what I'd say. I don't think there would be a difference in meaning in most contexts.
You can also say: "Young people find this movie boring" or "This movie bores young people" which means you can escape the choice of prepositions.
I would always add a 'usually' or 'most' somewhere in a sentence like that.