Removing hard moving grain on some spots only

[Platos]

I have a clip, which does demonstrate what type of problem i want to adress. It's about the grain on his forehead. The rest of the video does not contain so much grain in comparison to his forehead. Is there any option (which does not mean hand-edit-like), which does handle only the "bad ares" ? Like on dark scenes i can eliminate noise/grain with masking. I tired this too with masks (vsPlacebo + MCTemporalDenoiose), but it has no effect. Also, when you look at the preview with retinex you can't really see the moving grain. I guess that's why a mask does not have an effect.

has anyone an idea how to remove it without just increasing degraining-settings and without degrading the rest of the image to much ?

Video (5sec): https://uploadnow.io/f/NFwbHvw

[jagabo]

In a case like this you may be able to use a mask of fleshtones.

hsmask = MaskHS(StartHue=110, EndHue=135, MinSat=10, MaxSat=90, coring=false).BilinearResize(width, height)
Overlay(last, smdegrain(tr=2, thsad=500, PreFilter=6), mask=hsmask)

Tweak the settings to your preferences.

[Selur]

Maybe jus tuse smdegrain(tr=2, thsad=500, PreFilter=6) (prefilter=6 <>KNLMeansCL) on the whole thing without the masking,...