This guy is always informative and interesting to listen to. I'd recommend you watch them all because it shows just how masterful Naughty Dog is:
https://www.youtube.com/watch?v=LUX0zNr7YFE
Here is his breakdown of the original E3 demo:
https://www.youtube.com/watch?v=0ZFquhQiC88
And the breakdown of the PSX demo
https://www.youtube.com/watch?v=VcQ_VJX0BNo
The PS5 Exists.