How Browser download files (via HTTP or FTP)

Please forgive me if it seems silly question to you, I've this doubt and didn't found the answer on surfing web.

How browser and any other downloader downloads a file, Which protocol is working at the backend HTTP or FTP.

As we all know HTTP can be used to transfer text, which can be rendered by the browser on screen. It can also sends bianry data.

Lets say I want to access a webpage at http://ift.tt/1LJN7Fa which has a static webpage with 2 images. As we all know a total of 3 http requests will be made, one for webpage and other 2 for images.

But what about other files whose size is big. I mean suppsoe I'm downloading an mp3/mp4 files, who's link is given in webpage. So, what protocol is working at the backend HTTP or FTP.