That's great they took down the content but they failed to mention compensating the content creators who in all likelihood generate income from the videos that have now been viewed (free or not) by Udemy users. Way to maintain integrity.
In the Napster case, the fact that the infringing content drew in more users was enough to prove it was financially benefiting from the content. Even if Udemy refunds all the class fees for the infringing classes, they would still get the benefit of bringing in new users to their platform because of the infringing content.
In other words, it might be hard for them to claim safe harbor.