Gives a shorter url to media links in your media library.
It will redirect the URLs and make a flush to the rewrite rules in WordPress when activate and deactivate.
It's the tag that is included in the WordPress rewrite rules and makes a call to the MediaShort redirect.
Redirect means the URL will transform to the File URL given in the Media Library. Rewrite will not touch the MediaShort URL and persist the address for the visitors using the URL.
The alternatives will show in the Media Library Dialog and all of them will work as a substitute to the File URL.