The poster at 10:45 you show is the German poster. And he is not a "Poltergeister" but a "Lottergeist" which is a play on Poltergeist which could be translated as "Ruffian Ghost".
I always thought the ghouls in the background were just in another waiting room but I never really thought about it too deeply. Im glad you explained it, Pretty cool!
When I was a kid I always thought the man in the window was Otho as well. My explanation of him being there was that he had gotten his hands on the book for the recently deceased, allowing him a glimpse into the after life.
My friends and I were invited to a test screening of Beetlejuice at our mall, and we were blown away. By the way, our mall was featured in a movie called Back To The Future.
Omg, i just watched Beetlejuice again w/ my girls last weekend, lol. I actually am old enough to have seen in theaters & it was such an amazing experience. And yes, practical effects hold up 1000x better than CGI. 🥰🥰🥰