Hello,
The lesson says: "In the case of de + [people], the preposition de remains and is followed by a stress pronoun (moi, toi, lui, elle, nous, vous, eux, elles)"
But in the video, there's an example "Vous connaissez des francais?" and the answer is, "Oui, nous en connaissons". Shouldn't it be: "Oui, nous connaissons d'eux"?