Manual Overlay Left&Right

safe = Crop(2, 0, -2, 0)
ConvertToYV24()
 
base1 = Crop(2, 0, 0, 0)
left1 = Crop(0, 0, 1 - Width(), 0).Tweak(cont=1.03)
left2 = Crop(1, 0, 2 - Width(), 0).Tweak(cont=1.04)

StackHorizontal(left1, left2, base1)
 
base2 = Crop(0, 0, -2, 0)
right1 = Crop(Width() - 1, 0, -0, 0).Tweak(cont=1.03)
right2 = Crop(Width() - 2, 0, -1, 0).Tweak(cont=1.03)

StackHorizontal(base2, right2, right1)
 
ConvertToYV12()
Overlay(last, safe, x=2, y=0)

• You can play by tweaking contrast values to fix dirty lines (1 is default. Going bellow make the line darker, going over make the line lighter).
• You can add fixes for many lines you want, here is just an example for 2 pixels left and right.
• This didn't fix completly black lines, so please doesn't consider as a replacement for FillMargins.