The main key behind it is the use re 'eval', which allows Perl to be inside the (?{...}) considitonal regexps. Couple that with the "e" flag on s/// and it runs the loop. Now when it hits the do{}while($n), $_ is

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[download]

Hmmm, it looks like a bit of source code and a state engine to me!

--
$Stalag99{"URL"}="http://stalag99.keenspace.com";

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