The data you submitted *does* have newlines.

while (<DATA>) {
   my ($key, $val) = /^\s*([^:]*?)\s*:\s*(.*?)\s*$/
      or next;

   print("[$key:$val]\n");
}
[download]

and

while (<DATA>) {
   my ($key, $val) = split(/:/, $_, 2);
   next if not defined $val;
   s/^\s+//, s/\s+$// for $key, $val;

   print("[$key:$val]\n");
}
[download]

both do the trick.