Download Only files don't display in the secure content viewer and require download permissions for reviewers to access them. This content   is not searchable in your project.

Examples of Download Only files include: some audio/visual files (see Video Content Viewer for a list of video file types that do not require download access to view), zip files, or proprietary software files.
 
Some Download Only files are Bypass Files and upload without intervention; others may be sent to the Action Required area in Shortcuts. Within Action Required, items can be permanently deleted or set to Special Media and posted to the project.

Special Media files have no page count and are billed by size (MB).