Bleeding or clouding often occurs during dark sequences in movies and is more visible when you sit in a dimly lit room.
............................
Samsung has tried to eliminate backlight bleeding during movie watching by incorporating “LED zones” behind the panel in the areas where the black bars show up. In these zones Samsung can dim the backlight individually without affecting the rest of the image. Samsung calls it ”Cinema Black” and it eliminated bleeding issues in the black bars completely in the demonstration we saw. Samsung still uses global dimming when the entire image switches to black, for example during movie cut scenes.