youtube
that you can very quickly install on your Firefox download browser, lets you download videos from YouTube in common platforms like MP4 and FLV. Meanwhile, extensions that are other produce your checking safer. An example with this could be BetterPrivacy, which protects you from sites that mount probably damaging "tremendous cookies" on your own browser. Important thing: it is possible to customise the extras you need.
http://sourceforge.net/projects/free-youtube-downloader-fvdtube
5 out of 5 from 1 reviews