Well, that black tacky stuff was STILL tacky after about 16 hours later, so I just placed the vapor barrier back. Hopefully, it'll hold (It should. Man, that stuff is pretty strong).
Not a bad DIY. The hardest part was placing the new regulator inside the door. You just have to move some wires out of their holders and finagle it in without losing your patience.
After examining the old regulator, it looks like the white plastic "window holder" piece broke in the area where the cable connects to it. These damn BMW engineers can make an engine that is both powerful AND fuel-efficient, but yet they can't make regulator that can last ??
Shees....