I know YouTube is a terrible provider of pirated content and also that it is almost impossible to pirate without a VPN, but I would like to know: if I download a movie from YouTube (directly from it, of course) without a VPN, will I receive “that type of message” from my ISP?
They’re not indistinguishable, downloading a video results in the same amount of data being transferred much more quickly. But your ISP couldn’t care less either way.
Especially if you have simmetrical speeds for upload and download