Satanic messages [Puzzle] [Ended; solution posted]

Ends Oct 2, 2012 08:10 a.m. GMT+4. Requires $0.99 contribution. The game shall remain secret.

You can start by going here.

No hints. Everything you need to know is somewhere in the puzzle itself. Good luck.

Solution:
Puzzle name refers to the practice of backmasking. Or, more specifically, to the accusations made against bands like Judas Priest, whose songs allegedly contained "satanic messages" recorded backwards.

1) Reverse the track. You can do it with Audacity - free, open source program, the link to which I helpfully hid the source code. Open file -> Effects -> Reverse. Now you can listen to the message.
2) If you ever played any military shooter, you should know what the words in the message mean. It's the NATO phonetic alphabet. Message goes "Yankee Tango Romeo Hotel November Lima Echo", so that's YTRHNLE, a string of letters. Question is - what do you do with it?
3) Check the file's ID3 tags. There's a number 64 in the comments, suggesting you should use base64 to decode the string. But to decode it without the bits of gibberish, you need to know the correct capitalisation.
4) You've probably noticed, that there are two voices reading out the letters. It's actually one voice, but with altered pitch. Raised Chipmunkesque pitch = upper case letter, lowered slowish pitch = lower case.
5) So, the correct capitalisation is YTRhNlE, decode it and you get a4a6Q, which is a giveaway code.

Oh, and why is there a sound of rain in the background? Well, you need something in the background, otherwise it sounds ridiculous. And I just happen to like rain.