I don't know whether there is any batch job to search and print subscribers,
concealed or otherwise, but the program you posted would only search on
the *message* database for the list.  It was searching for messages which
may have contained the word "conceal" in the subject header of the messages.
 
What you might do is to send QUERY listname FOR *@* to Listserv (which
might generate a lot of output) and then in the output search for
"Conceal= Yes".
 
-- Roger Burns   [log in to unmask]