As a native french speaker I can say that the speech they recreated is much much faithful to De Gaulle's actual way to speak than the actors who played him.

De Gaulle had a very special way to talk, he talked extremely slowly exagerating the pronunciation of every word and making long pauses. I never heard an actor actually doing him perfectly, in Le Monde's video they are basically spot on, I don't think anyone could tell it's not De Gaulle with any certitude.