I got smacked on the head with confusion when I saw this in the results.
get this weirdness:
key1-key2-key3 as a query (with those dashes) hightlights key1key2key3.com in the SERP
key1 key2 key3 as a query does not.
only need to see it happen once to be certain google knows how to highlight in the middle of a concatenated url string - the fact that I can only reproduce it with a certain set of key1-key2-key3, and only with dashes, is all just fodder for confusion, but besides the point.
> ...certain google knows how to highlight in the middle of a concatenated url string...
I wonder if it is that way round. I suspect that the concatenation is performed before the search is run and highlighting conducted. Otherwise ste-rwo-rld [google.com] would match and "sterworld" would be highlighted in ste-rwo-rld OR "google news" [google.com]?