I expect it's true that they lose safe harbor, but I couldn't find anything saying that. Are you just guessing?
(c) Information Residing on Systems or Networks At Direction of Users.—
"(1)In general.—A service provider shall not be liable for monetary relief, or, except as provided in subsection (j), for injunctive or other equitable relief, for infringement of copyright by reason of the storage at the direction of a user of material that resides on a system or network controlled or operated by or for the service provider, if the service provider—"
...
"(B) does not receive a financial benefit directly attributable to the infringing activity, in a case in which the service provider has the right and ability to control such activity"[1]
That's the killer. This service not only charges, they charge on a per-course basis. That's direct financial benefit from the infringing activity.
That seems relatively easy to weasel your way out of. Just sell 'download tokens' which enable the user to download any course on the site they want. Whatever legal argument YouTube is using to protect themselves from this with their new premium subscription would also have to apply here.
I would say that it is clear that _if_ YT is breaking even or making a profit via ad impressions providing the service that they provide then it is _indirectly_ benefiting. No, they are not directly monetizing the (alleged copyright infringing) content but they traffic is driven to their site and eyeballs continue to be view pages because of said (alleged copyright infringing) content which in turn is monetized via ad impressions.
Which is why I have no problem with people running an ad blocker.