Hi Billy - The current version of Dynamic Forms does not currently support Secure File Folders. There are a few reasons why but the specific reason why is because once you do this, then you can no longer access files from the standard method but you must "Always" use the "LinkClick.aspx" tool to access those files. Basically this occurs for any folder within DotNetNuke as this is the only way within DNN you can secure files. We are working on a method for allowing this where we handle the code in a similar way (using FileID as a number in reference to the Files table) however this feature is not currently part of the module at this time unfortunately.
One thing you can usually do is ask Google note to ever try and index anything within those directories (not that they would anyway unless it was a hyperlink somewhere on your site). You can do use this by updating your robots.txt file.
I would also argue that using the "Unique / GUID" filename is actually just as secure as the file upload within the secure file. I guess I couldn't say "As secure" because if the user were to ever see a hyperlink in an email and saved it then they could always access that file, but the filename itself (a GUID) is generally used as a primary key because the value is so unique.
http://en.wikipedia.org/wiki/Unique_identifier Thanks!
-Chad