I read somewhere last week that youtube.com is moving towards a model where you can click a button to download the video you are looking at. This can be helpful if you are trying to show someone a video, but you don't have internet access where they are.
This idea is already being used by a couple of websites, however now you can simply add PWN to the address of the video and that will give you options for downloading it.
http://pwnyoutube.com/Â Is the site with some of the directions. However, all you need to do is add PWN to the address, so that it goes from this: