Continuous color motion

The Ring of Colour
Place a red or green filter over the moving pattern to accentuate the luminance difference between the moving colours. This will reveal the true motion speed.

The speed of the patterns is always the same and the overlay of luminance dots is added to suppress the luminance artifacts in the rotating rings (as suggested by Tom Troscianko and like the luminance noise in the Ishihara plates). To help judge the slowing, light spokes are shown in the centre, moving at the same rate as the inner colour pattern (there are two rings that rotate in opposite directions). If this demonstration works on your monitor, you can show that the slowing is in your perception and not in the video by placing place a red or green filter over the video or over your eye (maybe one half of a pair of red/green anaglyph glasses). The red and green in the display will then have very different luminances and the motion should be immediately apparent.