The actual file download links for filesonic look like:
http://s39.filesonic.com/download/32...7814bae56e420d
This link is contained on the page:
http://www.filesonic.com/file/r00021...gear_11_10.pdf

So in order to turn http://www.filesonic.com/file/r00021...gear_11_10.pdf into a valid download link DownloadStudio needs to parse the html returned by the request and find the download url. Or we can have a look a JDownloader and see what it's doing. We'll have a look at this next week and see if we can add this into DownloadStudio 7.0.

Until we make any changes, in order to download from filesonic you will need to visit the page that hosts the download link in your browser, e.g. http://www.filesonic.com/file/r00021...gear_11_10.pdf, and click on the download link so that DownloadStudio can catch the download for you.