I am going to "revive" this older thread, but just as a PSA.
After running into, for what what I believed, a tremendous amount of water dripping into my door on the correct side of the vapor barrier (I cannot attach the videos here unfortunately). After showing this to another owner, and the dealership, both have confirmed this to be normal on our cars. However, of the 3 door cards I have removed the Vapor barrier was very, very poorly installed and usually at the bottom. I get about 3-4 large drips of water in the door every second while it is raining outside, coming from the window slide assembly.
Since it is designed this way, and the doors have proper drainage to accommodate, the drip isn't a big deal. But if your vapor barrier is not installed correctly, this will lead to a lot of water leaking into your car and into the foot wells. Eventually leading to mold, mildew and smells. Also leaves a large concern for the longevity of speakers installed back there, I will be installing baffles on mine as an extra layer of protection.