DMCA 1201 is written so broadly that any feature of a product or service can be construed to prevent copying, and thus gain 1201 protection.

I don't think YouTube intended regular uploads to have DRM, if only because they support Creative Commons metadata on uploads, and Creative Commons specifically forbids the use of technical protection measures on CC-licensed content[0]. On a less moralistic note, applying encryption to all YouTube videos would be prohibitively expensive because DRM vendors charge $$$ for the tech.

But the RIAA wants DRM because, well, they don't want people taking what they have rightfully stolen. So YouTube engineered a weak form of URL obfuscation that would only stop very basic scrapers[1]. DMCA 1201 doesn't care about encryption or obfuscation, though. What it does care about is if something was intended to stop copying, and if so, if the defendant's product was designed to defeat that thing.

There's an interesting wrinkle in DMCA 1201 in that merely being able to defeat DRM does not make something illegal. Defeating DRM has to be the tool's only function[2], or you have to advertise the tool as being able to defeat DRM[3], in order to actually violate DMCA 1201. DRM vendors usually resort to encryption, because it makes the circumvention tools specialized enough that they have no other purpose and thus fall afoul of DMCA 1201. But there's nothing stopping you from using really basic schemes (ROT-13 your DVDs!) and still getting to sue for 1201.

Going back to the AI ripping question, this blog post is probably not in and of itself a circumvention tool[4], but anyone implementing it is very much making circumvention tools, which are illegal to distribute. Circumvention itself is also illegal, but only when there's an underlying copyright infringement. i.e. you can't just encrypt something that's public domain or uncopyrightable and sue anyone who decrypts it.

So the next question is: is AI copyrightable? And can you sue for 1201 circumvention for something that is fundamentally composed of someone else's copyrighted work that you don't own and haven't licensed?

[0] Additionally, there is a very large repository of CC-BY music from Kevin MacLeod that is used all over YouTube that would have to be removed or relicensed if the RIAA were to prevail on this case.

I have no idea if Kevin actually intends to enforce the no-DRM clause in this way, though. Kevin actually has a fairly loose interpretation of CC-BY. For example, nobody attributes his music correctly, either the way the license requires, or with Kevin's (legally insufficient) recommended attribution strings. He does sell commercial (non-attribution) licenses but I've yet to hear of any enforcement actions from him.

[1] To be clear, without DRM encryption, any video can be ripped by hooking standard HTML5 video APIs using an extension.

[2] Things with "limited commercial purposes" beyond breaking DRM may also be construed as circumvention tools under DMCA 1201.

[3] My favorite example: someone tried selling a VGA-to-composite adapter as a way to copy movies off Netflix. That is illegal under DMCA 1201.

[4] To be clear, this is NOT settled law, this is "get sued and find out if the Supreme Court likes you that day" law.