Dear William, thanks for answer !

let's try such command-line (version 3.33):

httrack -O "temp" <http://www.httrack.com/html/index.html>  "-*[>20]"

the response is such:
httrack -O "temp" <http://www.httrack.com/html/index.html>  "-*[
>20]"
Mirror launched on Mon, 31 Dec 2007 10:37:22 by HTTrack Website
Copier/3.33+swf
[XR&CO'2005]
mirroring <http://www.httrack.com/html/index.html> -*[>20] with the wizard
help..
Done.
Thanks for using HTTrack!

it will download one file (~7kb size) and then stops ! but it should download
all the website and filter files with size bigger than 20kb, dont it ?!..

if we remove -*[>20] then it will download all website as it should be.

if we change -*[>20] to +*[<20] then it will download all website and also
files really bigger than 20kb size

also, other my experiments shows that -*[>] filter is working only with files
with *.html extensions. while these days there are a lot of websites with
HTML-content, but *.php *.asp and other extensions.