Download youtube video directly from the command line with youtube-dl

If you keep searching for applications to <a class="zem_slink freebase/en/uploading_and_downloading" title="Uploading and downloading" rel="wikipedia" href="http://en.wikipedia.org/wiki/Uploading_and_downloading">download the <a class="zem_slink freebase/en/youtube" title="YouTube" rel="homepage" href="http://www.youtube.com/">youtube videos or you keep searching for the firefox addons to download the embedded the video, then this is for you. Ofcouse that is the case, only if you do not want to copy it after you have watched it in the <a class="zem_slink freebase/en/web_browser" title="Web browser" rel="wikipedia" href="http://en.wikipedia.org/wiki/Web_browser">browser :). If you have already watched it then you can copy it from the <a class="zem_slink freebase/en/mozilla_firefox" title="Firefox" rel="homepage" href="http://www.mozilla.com/en-US/firefox/">Firefox cache. I will post on that later for now lets see youtube-dl.