well, I didn't watch the entire long video - but I see the walls are nicely sealed, the floor grind must have been a real bear!, the double length blocks indicate the wall is more than the initial 12" - which is good - no way you could install insulation and drywall in a 12" "man way" - using pressure treated 2x4 is a waste, you are just not going to have enough water soaking the wood over enough time to make any difference. smooth move on the venting.
what did you decide on insulating the ceiling? most of the commenters did not read about what you are doing and hence there's a whole lot of bad advice on the topic. the idea of "no ceiling" again is one of those "just didn't read a thing" suggestions. if you need to a/c the room there is no sanity in leaving the top of the room open beamed.
info note: if the ceiling is 96.5" from floor (example only) you can't build/nail up a wall 96.5" tall on the floor and then tilt it up. have you thought about the precise steps to constructing the walls?