This. Your solution is fine, but you need to do a bit of postprocessing, e.g.

if (@groups = /$test_regexp/g) {
    while (@groups) {
        ($url, $file) = splice @groups, 0, 2;
        # ...
    }
}
[download]

or use a loop:

while (/$test_regexp/g) {
    ($url, $file) = ($1, $2);
    # ...
}
[download]