Oh, really? Then would you mind explaining the following pieces of software that let you download videos from YouTube?
https://addons.mozilla.org/en-US/firefox/addon/flashvideorep... http://downloadyoutubevideo.org/ http://keepvid.com/ http://saveyoutube.com/ https://addons.mozilla.org/en-US/firefox/addon/video-downloa... https://addons.mozilla.org/en-US/firefox/addon/easy-youtube-... https://addons.mozilla.org/en-US/firefox/addon/1-click-youtu...
Sure, you could say that you'd have to know about them, but all of the above can be found searching "download youtube video" from Google.