The lesson says you can't use the pronoun "en" to replace people. But then the first video gives multiple examples of doing just that. For example:
Vous connaissez des francais? Oui, nous en connaissons.
Cette homme aime une actrice? Oui, il en aime une.
Are these examples not correct? Or are they okay because it's not "de" + person? In that case, can you use "en" to replace people as long as "de" doesn't come before the people?