Wouldn't they even move different parts of the scene differently for summing up? And the summing is for denoising, not for rising levels out of darkness, so it

Wouldn't they even move different parts of the scene differently for summing up? And the summing is for denoising, not for rising levels out of darkness, so it would be perfectly fine to sum only the parts where there is plenty of confidence about the movement, leaving others noisy (or, if more noisy than one would like to admit, de-noise spatially instead of temporally in those places, which brings us back to blurry. Add an "unsharp mask" step to compensate and you get that watercolors look we all know). Back to moving different parts differently: this seems very similar to the motion prediction parts of video encoding. I wonder if and how much the stacking algorithms make direct use of elements of the video encoding implementations those cameras also have?