Approach to the Eye
First, start with a 3 minutes or 5 minutes video and stare intently. The image is not in focus. After a while, you will stop trying to focus and your eye muscles will relax.
Approach to the Brain
The video uses Gabor waves. This image can be easily recognized by the primary visual cortex (V1), but lacks information in the secondary visual cortex (V2). The aim is to stimulate V2 to work more actively to compensate. After watching for 3 minutes or 5 minutes, you will feel the contours become clearer.