4chan image/webm downloader

function dl {
    fold=$(echo "${1}" | perl -lane '($fold) = $_ =~ /thread\/(\d+)/; print $fold' | head -n1)
    mkdir -p "${fold}"
    echo -n "Downloading.."
    curl -s  "${1}" | perl -lane \
        'BEGIN {
            sub dl {
                my $str = shift;
                (my $URL) = $str =~ /href=\"\/\/(.+?)\"/;
                (my $title) = $str =~ /\<a title\=/ ? $str =~ /title=\"(.+?)\"/ : $str =~ /target=\"_blank\">(.+?)\<\/a\>/;
                $title =~ s/\s+/_/g;
                print "$URL $title";
            }
        }{
            (my @a) = $_ =~ /div class=\"fileText\"(.+?)<\/div>/g;
            foreach $a (@a){
                &dl($a)
            }
        }' | while read URL title; do
            if [[ ! -e "${fold}/${title}" ]]; then
                curl -s  "${URL}" > "${fold}/${title}"
                echo -n "."
            fi
    done
    echo
}

### Usage:
# dl http://boards.4chan.org/b/thread/########