Skeuomorphs are cultural algorithms, borrowing functional forms of the past to make the new objects of similar function more comfortably familiar. The ribs on the handle of a knife are skeuomorphic of the vines wrapped on the hand end of a sharpened stone.
Apple's felt or leather served no functional purpose. They are faux realism, not skeuomorphism. Similarly, a digitally simulated voltmeter is not skeuomorphic, it is not a new object made familiar by borrowing a past form. It's just a digital replica.
Meanwhile, buttons with drop shadows, buttons that appear to depress complete with haptic feedback, are skeuomorphic. Apple Notes being yellow lined note paper could be called skeumorphic. And certainly, the rolodex tabs for letter groups in Contacts were clearly skeuomorphic.
This is an interesting video, and it initially defines the term correctly, but then incorrectly buckets many things as skeuomorphic to make a point, when in fact the objected to them tended to be they were not skeuomorphic at all.
Borrowing functional forms of the past to make new affordances comfortable and familiar, given them the right feel in your use, remains a good idea, at least for a transitional time.