What are the settings that you use (noise, blur, face refinement)?
I use GP a lot and I have found that the main problem in frame by frame processed videos is with the stars : they are “split” (GigaPixel redraws two sharpened stars instead of one blurred) and they move from frame to frame.
It seems to me that you also have this problem in your video. Did you achieve to reduce or solve it?
I know exactly what you are talking about. I personally have found the best results are on low/low anything more than that just amplifies the mistakes Gigapixel is making. I’ve been thinking about doing a double pass, at low/low and then just a plain scale with no image improvement, and layering the two images to try and reduce the enhanced noise/small details that become distorted.