It sounds quite a bit like the squeaks I was getting from loose interior door trim on my passenger side. It was slightly worse at certain speeds on pavement with just the right roughness (including on highways between 55 and 68 mph, if I recall correctly). It was driving me slowly insane.
It didn't vary with rain, but did vary with temperature quite a bit.
The door trim connectors weren't pushed into the metal door fully, so it was moving in and out a little, particularly at the bottom front, near the speaker. I think it was also allowing the speaker to move a little, which sometimes caused additional squeaks and pops beyond the squeak from the loose door trim.
It wasn't super loose, but enough where the gap between the front bottom of the door trim and the metal interior of the door was noticeable (about 3/16", pullable to more with gentle force). The mobile service guy was initially skeptical that was the issue, but it definitely was. It all went away after he replaced the connectors and secured it properly.
One way to test it is to find a stretch of road and a range of speeds that tend to bring out the noise, then push the trim against the door at different points and see if it helps.
R,
Bill