A good many file hosting sites aren't allowing the general public to access their results in search returns online, and while there are un-official search engines and file-indexes do exist for a few, but not for all of them.
Site search commands can be used to search for software, videos, music and other files:
For albums or songs, include the artist, album or song name:
site:filehoster.com mp3|wma|ogg "type your search query here"
For videos, use this:
site:filehoster.com asf|rm|avi|mp4|wmv|flv "type your search query here"
For graphic novels, use this:
site:filehoster.com cbr|cbz "comic name here"
For compressed file-archives and software:
site:filehoster.com rar|zip|exe "type your search query here"