An artifact of composite video sources in which dots seem to crawl between contrasting colors. This is the result of an inexpensive comb filter that does not entirely separate the luma from the chroma (the black & white from the color). Also called "cross-luma."
Dot crawl (cross-luma) is noticeable at the boundary of contrasting colors such as blue and yellow. (Image courtesy of Home Theater and High Fidelity, www.hometheaterhifi.com)