Derrida knows that you're thinking about him now. He's thinking about the words that are on this page and the circumstances which brought about this writing. He knows I just finished my chicken sandwich and he knows I've only seen 20 minutes so far. He knows that the words were forming in my head as he talked, and I felt compelled to write them down, as if they would dissipate immediately as he continued to talk.
If deconstructionism is already taking place before we watch a film, then there's little additional benefit in watching this documentary because an obscurantist like Derrida participating so reluctantly in the interview and yet at the same time demanding us to read him is double-standard.