Hey man,
this looks very good to me. I am really waiting for a download hack for vB.
Just a few questions:
1. Can you include a rights system for every category?
Example:
Category A can only be accessed from admins and mods
Category B can be accessed from all users
2. It would be good to have a directory where you can upload files to via FTP and then tell the download script to include files in this directory for Category ABC.
Often is the case that you can't upload large files via the web browser.
3. Some small statistics would be nice.
How many files and cats are there?
How many files were already downloaded per category?
How often was a single file downloaded?
How many traffic (all downloads) was used so far?
4. Allow a special usergroup to upload files to a defined category.
This will allow you later on to create a group which can upload files to a category and keep them up to date. There is no need that only the admin can do so
5. Buy access to a downloadcategory using the vBulletin payed subscription routine. User which payed a defined amount of money via paypal have access to a special download area for X days.
Ok these are only a few suggestions but maybe you can think about implementing those points.