Ever wondered how to download YouTube videos and play them offline? Below will guide you how to do that but most are applicable only to Mozilla Firefox browser though I mentioned one for Microsoft Internet Explorer.
Video file is downloaded to cache in Firefox for viewing. When viewing is completed, the cache file will be deleted. To permanently download a YouTube video, you need a Firefox addon or third party program
https://addons.mozilla.org/en-US/firefox/addon/3006
https://addons.mozilla.org/firefox/addon/3590
http://www.sothinkmedia.com/
http://lifehacker.com/software/exclusive-lifehacker-download/better-youtube-firefox-extension-319925.php
http://googlesystem.blogspot.com/2008/04/download-youtube-videos-as-mp4-files.html
For Microsoft Internet Explorer, try below
http://www.downloadyoutubevideos.com/
