[AndyB] Disallowed extensions 1.0

Disallows selected attachment file extensions in posts.

This add-on is useful if you allow video attachments. By default XenForo allows all video types. So for example if you only want to allow MP4 videos then you can disallow the other video types.

(Example of Options page)
(Example when user uploads disallowed extension)



Features:
All phrases start with disallowedextensions_ for your convenience.