They're looking for matching pattern fragments. One good way to visualize how they're assessing that is to take a look at the Genome Projector's DNA walk view. Looks like this: https://i.imgur.com/z3etcmy.png
What they've done is assigned A/T/C/G to North/South/West/East and ended up with that walk plot. They go into some detail on the overview page about the significance of the plot, but overall point is that "DNA Walk makes patterns in the genomes sequences apparent. Clustering of repeats, palindromes, horizontally transferred genes, telomeres, and GC skew can be easily spotted using this visualization approach."
What they've done is assigned A/T/C/G to North/South/West/East and ended up with that walk plot. They go into some detail on the overview page about the significance of the plot, but overall point is that "DNA Walk makes patterns in the genomes sequences apparent. Clustering of repeats, palindromes, horizontally transferred genes, telomeres, and GC skew can be easily spotted using this visualization approach."
Interactive E. Coli link can be seen at http://www.g-language.org/g3/ (click on the DNA Walk tab view).