Watch the rotating clock hand when the bright rim dot flashes. The hand and flash are physically aligned, yet the flash may appear slightly behind the moving hand. Focus on the outer edge and compare their positions in this optical illusion.
Music: "Interloper" by Kevin MacLeod (incompetech.com), licensed CC BY 3.0 US. Excerpt trimmed to 30 seconds and mixed with this video.
Source: https://commons.wikimedia.org/wiki/File:Interloper_(MacLeod,_Kevin)_(ISRC_USUAN1100401).oga
License: https://creativecommons.org/licenses/by/3.0/us/deed.en