johngg has already mentioned the possible issue, but it seems you did not notice. I would suggest that it would be safer to use a non-greedy quantifier:

if ($data =~ m|<REDIRECTURL>(.*?)</REDIRECTURL>| ) {
print "Found: $1\n";
}
[download]

just in case there are two <REDIRECTURL>...</REDIRECTURL> pairs of tags (assuming this is possible).