When you are publishing media online, and you view it in your browser to check that it is OK, if the URL begins with file:// (or local:// for that matter) then the thing you are looking at is on your computer. It is not yet published on the inter web thingie. Things published on the web all must have the http or https prefix (HyerText Transfer Protocol). To publish it, if it is a stand alone web page/project (like a Korsakow film) you usually use FTP (File Transfer Protocol) to transfer it to a web server.