If I ever get to watch more episodes (I really lack the time) and get to a point where it changes, I'll possibly revise my perspective, but from what I've watched, apart from the streaming equipment, it really looks like a band of friends having great fun, and without a lot of acting from most of the crew, actually.
The greatness of a good performer is that they make it look easy.
If it didn't just look like a band of friends having fun ... then they wouldn't be great performers. If you have the chance, try watching a recorded game of pure amateurs (not performers) playing D&D some time and contrast what you're seeing.
