[kronusaturn]

That's called Troxler's fading, caused by the gradual adaptation of photoreceptors in the retina to the recent average light level. But in the OP, the yellow dots are high in contrast, disappear in less than 5 seconds, and then seem to blink on and off at random. So I think this might not be the same effect.

http://en.wikipedia.org/wiki/Troxler%27s_fading