Grayjay may not be bound to TOS but users of Grayjay are still accessing YouTube services in a way YouTube would prefer they didn't. OTOH videos are available without having to log in or having an account at all so I don't know if there's any implicit agreement between someone accessing a URL and the service provider.
True. And they might close your account if you login.
How I display, download or request data without an account and which browser or app I use to do it is still my choice. I'd guess if they could do anything about it, they would have half a year ago. The only way would be to DRM/widevine all videos and apparently they aren't ready for that yet. If they block my IP I'll just get a new one.
I wouldn't even be thinking about using a 3rd party app or blocking the ads if their service was reasonable. No way I will endure that, if they block it I'll just watch something else.
I don't think that's a problem: you can browse to YouTube's home page and search for and watch videos without logging in. Grayjay is just another user agent, as if it was another web browser.
