Well guys, I just finished up working on the seal. I don't believe it's a problem with water "inside" the door, but water being "splashed" up on the seal, or running down the side of the door and just getting trapped between the seal and outside surface of the bottom of the door.
When I pulled the seal off, I did it a section at a time. Approx. 6 to 10 inches long. My car looked as if it had a white "caulking" like material very thinly applied behind the seal. When I got the seal pulled out, it was completely wet on the inside. I wiped the trough off and the seal, and sprayed on the silicone lubricant. (Make sure you don't use a petroleum base lubricant because that will "degrade" the rubber seal) Fortunately there was no rust starting anywhere.
Andrew, I can't thank you enough for pointing out this "problem" area and bringing it to the forums attention. You truly are a life saver.
This is something I never would have ever thought about, and even though my car sits out the winters in my garage, it would have been silently rusting away due to the trapped water under the seal.
I highly recommend every XF owner address this situation as soon as you can, before it starts looking like Andrews photos.
An ounce of prevention is truly worth a pound of cure in this case.