- Illegal
I download some conference videos from YouTube to watch on my train journey. I can't stream them because reception on the train isn't good enough. It's the only place I can find the videos (they're not available for sale) and I don't share them with anybody afterwards.
I don't consider that to be unethical, and I don't imagine the police are going to hunt me down.
It's a bit worrying how many people run to defend corporation profits by default.
Not the OP but I don't think it has anything to do with corporation profits. If I spend money creating a video, put it on Youtube, and try to recoup costs through ads you're bypassing that by downloading the video with this tool.
99% of the people and organizations in YouTube never recoup costs. For almost all this is wishful thinking.
The bits are on my computer. I get that I can't just go redistributing it (legally), and that youtube probably doesn't _like_ it, but if it's illegal (and honestly, maybe it is in the US given how ridiculous copyright and licensing law is there) that's ridiculous.
Germany introduced a poorly-worded cybercrime law that basically made all network tools illegal (including nmap, wi-spy), but also disassemblers, on the basis that they "could be used in digital crime".
It's similar to making cars illegal because of a traffic fatality.
It's more about the intent than about what software you use.
once something is published on the internet then it is assumed it can be viewed / copied / downloaded / etc.
see https://en.wikipedia.org/wiki/Web_scraping , the legal issues part.