my @links = $res->find_all_links( url_regex => /\bvar=/ );
foreach my $link (@links){
  # $link is a WWW::Mechanize::Link object
  next unless $link->url =~ /\bvar=([^&?]+)/;  # this RE will need tweaking
  warn "URL is " . $link->url;
  warn "Value is '$1'";
}