In the Media > DCIM > subfolders, iBrowse is displaying numerous .mov and .jpg files NOT displayed in Camera Roll, Videos, My Photo Stream or any other album. Based on the throwaway content of the videos clips absent from the iPhone, but remaining in the DCIM subfolders, is it reasonable to surmise that these files were previously deleted, but remain unpurged and are still hogging available storage?
Can these video and image files be safely deleted from the DCIM subfolders, without angering the IOS stability gods? If so, can the corresponding thumbnails in Media > Photodata > Thumbnails > V2 > DCIM > Subfolders also be manually deleted?
If you see photo or video files in your Media/DCIM folders that are not visible in the Photos app, that means they are not in the photos database and are basically rogue or orphaned files. I’m not sure what would have caused it in your case, but you can safely delete them and any thumbnail files without angering the iOS stability gods :).
If any of the photos are important, I would definitely transfer them to your computer before deleting any files. Just drag/drop them to your computer or right-click and choose Export to folder.