How does a file product work now?

I've got the latest CVS and I've got the private upload module installed, but the file products thing has me stumped. File product is enabled and I've got an option to create a file download product, but it doesn't seem to do anything different to the other product types. On ecsettings/ptypes/file/add_feature ther'es nothing about file products.

Has it changed how it works quite significantly? When I create a file download product there's no box for me to upload a file or enter a file product path. There's a file attachments box, but it doesn't seem to work - when I upload a file there it thinks for a while but my file never appears in the attachment list and I'm not sure if that's where I should be attaching a download product anyway.

So my question is really: How do I make a file download product?