http[s]://sub.domain.top/ABCDEFG/url/goes/on*
with
/[A-Z]+/ or /[A-Z]{3,}/
But this filters quite anything, not only capitals.

Seams to be a bug.
Well, I have not such an option in the preferences. Where should it be? Should I search it in "about:config"?Sergei Z wrote:what u r probably missing here is turning Option IgnoreCase to ON (true). If u do that then u can match/filter on those ABCDEF by using pattern
Well, that's what I meant to say.Sergei Z wrote:sorry cannot help you here, I dont use Firefox and Adblock. I'm sure though the regex engine u r using must have such common option as IgnoreCase.