JDownloader is a free, open-source application that will help you download files from several different hosting services on the internet, optimizing downloads and letting you manage multiple active transfers from its own interface.
One of the features that has made JDownloader a success is its capacity of easily downloading files from services such as MegaUpload and Rapidshare, automatically and sequentially processing all files you add to the queue, whether you are a premium user or not.
The program could become your main downloads manager, bringing all your standard internet downloads, those from special services, and even special formats such as Youtube videos, into one place. By copying the Youtube videos' URLs into the program you’ll be able to download them locally.
JDownloader is written completely in JAVA, so it can not only be run on Windows, but also on other systems such as GNU/Linux and Macintosh. Because of all this, JDownloader, is a very interesting application for users who download several files from the internet daily and who want to automate the whole process.