For Example, to search all music files hosted on MediaFire type this in Google:
site:mediafire.com mp3|wma|ogg
Or for a specific artist, album or song include the artist, album or song name:
site:mediafire.com mp3|wma|ogg "type your artist, album or song name here"
For video files, use this:
site:mediafire.com asf|rm|avi|mp4|wmv|flv "type your artist, album or video name here"
For Comics, use this:
site:mediafire.com cbr|cbz "Comic name here"
For compressed file-archives and software:
site:mediafire.com rar|zip|exe "Search Query Here"