If your playlist doesn't work, one reason could be the difference between the paths used in the playlist and the URL in your browser.
It is necessary to create a crossdomain.xml file at the root of the site hosting the file. It must contain the domains authorized to load the files.
And here comes the solution for this problem:
<?xml version="1.0"?>
<!DOCTYPE cross-domain-policy SYSTEM "http://www.macromedia.com/xml/dtds/cross-domain-policy.dtd">
<cross-domain-policy>
<allow-access-from domain="www.yoursite.com" />
<allow-access-from domain="yoursite.com" />
<allow-access-from domain="subdomain.yoursite.com" />
<allow-access-from domain="www.from-another-server.com" />
<allow-access-from domain="from-another-server.com" />
<allow-access-from domain="subdomain.from-another-server.com" />
</cross-domain-policy>
Unix Servers require case sensitive letters!
That means, if your website is hosted on an Unix Server (like most websites) and your playlist file is called PLAYLIST.TXT, do not type playlist.txt in the module administration - this will not work.
Generally it's always a good idea to use lowercase letters for all file names.