What you are seeing is called dithering and it is common to all LCD monitors that use TN panels such as the Samsung PX2370. TN panels can only create 256k actual colors, thru dithering it can blend up to 16.7m colors. Sometimes you will seeing the "dithering effect" especially when a color shifts in brightness like what you see above.
There is nothing you can really do short of replacing you monitor with a more expensive monitor that uses a VA, H-IPS or S-IPS panel which can truly create 16.7m colors. You can try adjusting the brightness and contrast, but that won't help much.
Also, sometimes you will see a dithering effect in videos / commercials because of the way it was produced. Even watching those on VA or IPS monitor will still...