This visual phenomenon is taken to another level by drawing it, along with a cutout that "proves" it, and providing links to the same drawing and proof cutout that you see in the video. Feel free to use these items as guides for drawing it yourself, or just print them out to see that this unbelievable illusion is actually believable!
See/print the drawing:
See/print the proof cutout:
See the formal, full Instructable: