This article will describe how Firefox handles downloads for different types of files and how you can change that behavior.
When you click a link to download a file, the Internet Media type, also called the MIME type or Content type, determines what action Firefox will take. You may already have a plugin installed that will automatically handle the download. Other times, you may see a dialog asking whether you want to save the file or open it with a specific application. When you tell Firefox to open or save the file and also check the option to "Do this automatically for files like this from now on" (see below), an entry appears for that type of file in the Firefox Applications panel.
This will not affect media embedded in a web page - only links to the files themselves.