Jdownloader

Try plowshare (the git version is the easiest to install):
https://trisquel.info/en/wiki/how-download-file-sharing-websites-using-plowshare

If you're just looking for a download manager, I use KGet. It's the only download manager not built into a web browser that I've ever used, so I don't know how it compares to others. You can integrate it with Abrowser via the FlashGot extension.

There is "youtube-dl", a great CLI package to download videos from many websites, available in Trisquel repos -- after installing, run "sudo youtube-dl -U" periodically in order to use its latest version.

Also, there is Tucan -- http://www.tucaneando.com/ --, a graphical program to download files from websites available in Trisquel repos, but seemingly a virtual package...