We can't say that JDownloader for Mac is very user friendly, but for more-experienced users willing to put in some time on the front end to learn about the app, it proves to be a very capable tool for downloading content from the Web.
JDownloader has some great features, but offers little in the way of user guidance for its busy interface. If you don't spend time getting a few helpful tips from the publisher's forums, you may end up with the same video file downloaded in multiple formats, which you will trash. The whole point of the app is to try to save you time, not waste it, so we suggest you get up to speed before using JDownloader. Once you get the hang of it, it turns out to be fairly easy to use. As you browse the Web for content, and find something you may want to have on your Mac, all you have to do is use the Linkgrabber tab to add the URL, and JDownloader does the rest. We found that it did a good job downloading content from all types of sources in multiple formats, including FLV, MP3, MP4 and WebM, at different quality levels. You can also easily choose to look only for specific file types, which helps speed things up even more. In addition to selecting the directory you want to save certain file types to, JDownload will also enter those captcha codes you typically need to enter manually to prove you're a human.
JDownloader isn't for the novice user, and its user interface isn't as intuitive as you'd expect from this type of application, but it excels at its primary function: downloading your favorite content from the Web.