Thanks for this plugin.
I'm not sure this is a bug or specific to my site (or caused by another plugin), but after users entered their details some downloads would not appear and the arrows would constantly spin around. While in different posts the downloads would appear fine.
After three hours of playing around I have found it was the "&" character. If this "&" was in the download title or even in the post title the download would not appear and you would get into an endless loop.
Can someone else confirm.