First real ride and the seat is quite nice! Rat-ina frame all day long, no edit there...Hoping you keep the rat-ina on the frame, I'd go middle stem as well. That seat should fit your vibe, if not your anatomy.
Thing about BMX seats is, nobody hardly ever sat on them. Big boy BMX cruiser is a little different. But for showing the bike, and a brief ride video, it should work well!