Tente DownloadHelper para Firefox .
Just surf the Web as you are used to, when DownloadHelper detects it can do something for you, the icon gets animated and a menu allows you to download files by simply clicking an item
For instance, if you go to a YouTube page, you'll be able to download the video directly on your file system. It also works with MySpace, Google videos, DailyMotion, Porkolt, iFilm, DreamHost and others.
(ênfase em bloquear minha). Livre e funciona bem!
Eu tentei o vídeo em particular que você vinculou, e posso baixá-lo com o addon que mencionei acima.