> Need Website Builder (regex experts) help!
> How to find out the regex of the site (galleries)?
HTTrack does not support real regular expressions, it mostly is just * for any
character zero or more times and some other special constructs.

See the "Filters" part at <http://www.httrack.com/html/fcguide.html>.

Usually it manages to interpret even strange approximate filters.

You have to provide more information if you want specific help anyhow.