Dumb question but if I download a movie from YouTube do I get "that kind message" from my ISP?
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?
Your ISP cannot differentiate between weather the YouTube app is streaming the video or any program is downloading the video.
No to be pedantic, but this isn't true. If you're watching via the YouTube app, the content is served via chunks, and not in one continuous stream. I'm sure it would depend on the ISP, but they could potentially be able to differentiate the two.
Regarding that argument: Basically throttle the download to watch time (e.g. 5mbps for 1080p).
This way it would look like it's constantly refreshing the buffer.