"(3) As used in this subsection— (A) to “circumvent a technological measure” means to descramble a scrambled work, to decrypt an encrypted work, or otherwise to avoid, bypass, remove, deactivate, or impair a technological measure, without the authority of the copyright owner; and (B) a technological measure “effectively controls access to a work” if the measure, in the ordinary course of its operation, requires the application of information, or a process or a treatment, with the authority of the copyright owner, to gain access to the work"
The argument would seemingly be that youtube is in no way "effectively controlling access to a work." And none of the peculiar details of it's implementation are designed to operate in this capacity. Quite the opposite, it's technology is designed to broadcast, for the purposes of inserting ads, content to anyone who merely requests it.
Moreover, youtube is in no way connecting the "authority of the copyright owner" with the particular videos on it's site and has nothing but an ad-hoc system with limited availability that takes action only after content is uploaded. As there are many videos that are past copyright protection or have been explicitly released into the public domain, and they make no distinction in the "technical measures" used in those videos, that they aren't effectively controlling access, and the tools aren't circumventing them for this purpose.