I don't remember signing a contract with YouTube. They send my browser a list of "things" and their URLs required to render a page and, as my agent, my browser can freely load or ignore them.
> access, reproduce, download, distribute, transmit, broadcast, display, sell, license, alter, modify or otherwise use any part of the Service or any Content except: (a) as expressly authorized by the Service; or (b) with prior written permission from YouTube and, if applicable, the respective rights holders;
> circumvent, disable, fraudulently engage with, or otherwise interfere with any part of the Service (or attempt to do any of these things), including security-related features or features that (a) prevent or restrict the copying or other use of Content or (b) limit the use of the Service or Content;
> Please read this Agreement carefully and make sure you understand it.
> If you do not understand the Agreement, or do not accept any part of it, then you may not use the Service.
Even if it's not binding, it illustrates what Google intends to do (stop providing the service via an anti-adblocker script) if you do not follow their TOS.
Yes. They have complete discretion over what 'list of "things" and their URLs required to render a page' they decide to send any particular user agent (modulo copyright infringement, hate speech laws, etc.). There is no requirement that HTTP connections to 'youtube.com' should receive video data; or even HTML; or even that anything's listening on that port.
It doesn't matter what Google intends to do. Only what I do in response. TOS are not legally binding, they're a bunch of crap.
I want Google to pay my rent for the next decade, and Sundar has to offer a naked lapdance at the Pink Poodle every time they send me an ad I did not explicitly request to be shown.
Contracts are only valid if signed.