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?
nope. the ISPs track torrent downloads is by leeching off of the popular public ones, and checking if any of the peers have IPs that belong to them. not by analyzing each customer’s traffic individually.
downloading a video off youtube makes a simple HTTP download which wont trip any ISP alerts. especially since it’s a trusted domain like Youtube
Most ISPs don’t do that, content owners do then send complaints to the ISP who forwards them to the user. ISPs aren’t going to spend money on losing a customer.