Maybe watch the hurdy gurdy video side by side, I believe there's a filmed section of the narrator in there. He's been making these highly detailed videos for a long time and has spent years on this video alone. I highly doubt there's any AI involved.

Edit: not sure when this happened but it appears many videos of his face have been removed from both channels so maybe don't go looking since it seems he doesn't want to be found but rest assured that Fredrik Knudsen is a real person who just sounds like that