Here some philosophical stuff: Bird Analogy: https://www.youtube.com/watch?v=QmltIMPMeP0 On Reality: https://www.youtube.com/watch?v=5-SJKJnZ9cg
Here is a two part interview where he talks computer science stuff. https://www.youtube.com/watch?v=HXwNTw4I6Ok https://www.youtube.com/watch?v=LTiRWN5T0Gw
It's a fairly well-documented phenomenon that people suffering from things like dimensia or alzheimers will behave inappropriately, in ways they wouldn't have earlier in life.
Whether they're expressing deep-seated beliefs or simply no longer able to filter invasive thoughts is hard to say. The brain is a complex system and damage caused by trauma or exposure to lead, for example, can also cause increased impulsiveness and social aggression.
I can't imagine how terrifying it must be to slowly lose control of your mind and 'self'.
Take a look at his original account on here and you will find some - but also, there are many videos in which he has lasting moments of lucidity. Typically when talking about his old hobbies and passions.
Completely normal and not even slightly unhinged conversation - one would never know he was otherwise the ways he were.
https://www.youtube.com/watch?v=oH41gGBVpkE
His last Video. Aug. 11, 2018.