Do the video settings affect the visibility of cloaked units?

Playing on the lowest video settings (everything on low) allows for easier distinction of the blur that the cloaked units generate. Higher video settings enhances the background terrain making it harder to see the blur.

All cloaked units distort the graphics a little bit, even burrowed moving infestors/roaches will show up as slightly darker spots on the terrain.

The amount that the players play train their eyesight to recognize these blurs to instantly spot that their screen looks just a little bit off is an indicator for them to scan and kill the Observer/DT, etc.

Here's a clip showing the Infestor/Roach movement: