unscrambling a link

I don't know much about programming and I'm trying to unscramble this link. It's the last part of the URL, but I don't understand how the scripts on that site make a URL of it.

http://trailerzone.info/wait2.php?u=nUE0pQbiY3q3ql5gMJquqKOfo2SxYzAioF8/MQ1FA09DF0yDEj==

I'll post the bits that I think may be important.

document.write(''); document.write(''); document.write('');

var preferrer='';
try {
    preferrer = top.document.referrer;
} catch (e) {
    preferrer = '';
} finally {
    document.write('<scr' + 'ipt type="text\/javascript" src="http://www.sponsorads.de/a_script.php?s=158036&pref=' + escape(preferrer) + '&ref=' + escape(document.referrer) + '&ck=1"><\/scr' + 'ipt>');}

If you could point me in the right direction, that'd be very much appreciated.