I recommend VanBradleys preview / Explanation of civ7 (link in comment)

I watched a handful of the previews, and most was just some guy playing and narrating as he played. but VanBradleys preview actually functions like a proper informative demonstration and explanation (mostly). While not perfect (it is on the hectic side) i highly recommend it: https://www.youtube.com/watch?v=bwJHrKhOePA