This is mostly leftover before computers were a thing (think cassettes and paper copiers).
In practice, it's a racket and OSA is a mafia that doesn't pay to anyone. Also, the fees are rather small considering the the purpose (I think it's capped at ~$5 per device), but since authors don't actually get money from it(OSA practices) , it doesn't really matter.
Anyway, downloading audiovisual media is fine, seeding is not.