The bottom one has a more "sharper" or "higher" buzzing compared to the top one, kind of electrical as M79L suggested. Top one has less noise in the beginning and sounds maybe more "plasticky" vibration, like you suggested. So not exactly the same noise in them, but there is still some in both of them.Yes, that's what I'm saying about the lower clip - it still has buzzing.
I just re-watched the top one, and at around 2:30 onwards there is some vibration noise over the poor road surface at that point. This may or may not be the same buzzing noise. The road roar is more noticeable than the vibration noises so it's difficult to tell. I'm not that concerned as I didn't notice it the first time I watched this clip whereas in my 2nd run clip it was very noticeable. And that was over a very smooth road surface.
But as you said, unless you're going to religiously relive your driving moments every evening, those noises should not matter. And they should not matter in an accident either as they are not blocking any other sounds. Probably more hassle to start a replacement process, than just to live with it that 1 time when you catch some action. And even then, you probably should delete the sound track before uploading it to Youtube (unless it's an aircraft crash landing in front of you, then the sounds would be okay).
(Off to install my A119, let's see if mine has any extra noises ).