Biden - "He's sharp as a tack" "He runs circles around me"
To be fair, we can't see what he is doing while talking. I hear papers shuffling so it could be he is reading notes or something while trying to refresh him memory. I have no doubt Biden was losing his faculties during, and even before, his presidency. That is not in question for me. But it is possible, and not uncommon, for people going through this to have moments of coherence, even hours.
I am certain, they only exposed Joe Biden to outsiders after pumping him up with drugs and making sure he was having a "good" day.
On the other hand, If he was not shuffling papers or reading while talking then he was far worse than I thought at the time - and I thought he was pretty bad.