The WordPress media library is fairly decent for uploading multiple files at once from your computer. However, copying hundreds of files from another location on your server is another story.
You might think that you could simply drop the files into your uploads folder and have them appear in your media library. This is not the case, because WordPress will not recognize those files unless they come through the dashboard uploader.
The Add From Server plugin offers a solution to this problem. It allows you to import media and files into the WordPress uploads manager from any location on your server.
As you may be able to tell from this screenshot, in this situation I was pulling product files from the downloadables folder within a site using WP E-Commerce. I needed to move hundreds of audio and video files to a brand new WordPress installation where I will be using MarketPress, since it has superior handling for free products and discount codes.
The Add From Server plugin is the only solution I could find for the problem of getting WordPress to recognize media files in the library when transferred via FTP. However, if you know of another one, please leave a note in the comments.
Though the plugin appears not to have been updated for nearly a year, I can assure you that it works perfectly with WordPress 3.1.2. I thoroughly tested it by transferring hundreds of very large media files, and I didn’t receive any errors whatsoever. Without this plugin I would have spent hours downloading these files to my local machine and then re-uploading them to the new installation through the media uploader. Get your hands on the Add From Server plugin if you’re in the same situation and you’ll save yourself loads of time.