About remote upload, I give an example, here is my avatar url:
http://img2.pict.com/63/b1/24/dca731...KL/avatar2.jpg
then enter this url for remote uploading; it means as long as you can get the url of a file, you don't need to upload it from your computer but just upload it from other servers, that's why it is called remote, to put this process simply, hotfile.com download those files directly. So I think it supports files end in .jpg/.rar/.rmvb/.avi etc. that can be directly downloaded, but torrent is not allowed for it needs P2P software to make download possible.
Well, some softwares like flashget can download both normal downloads and PTP network downloads.
Anyway, thanks for the information about remote upload. Just now read their FAQ and I found the below writing. Does that mean we have to give away our username and password in the public? Can't anyone who download our file see the username and password?

How to fetch files from other file hostings as RapidShare
Put as download URL:
http://username:password@rapidshare....DRip.part4.rar
Where usernameassword are your password to your RapidShare account