Also you can do executions "inside" the regex, e.g.:

qcode => sub {
        while ( $data =~ /^(?!(?:0|15|16|31)\D)(\d+)\N{SPACE}
                           (?!(?:0|15|16|31)\D)(\d+)\N{SPACE}
                           (?{ 0 and print "[$1, $2, or match further]
+" })
                           /mgx ) {
        }
        return 1
    },
[download]

(??{}) works faster in this case, but the final value can "accidentally" match.
But it's just about the placing.