Here is an add-on for Google Chrome that makes downloading videos from YouTube much easier. Users can download YouTube video in either MP4 or FLV format just with a click.
(There is another method for downloading YouTube video directly from Google Chrome, click here to see how)
The above mentioned chrome extension allows users to download a YouTube video in either MP4 or FLV format. The required format can be selected in the extension 'options' page. (See screen shot)
The Video Downloader icon appears on pages where you are viewing a YouTube video. Clicking on this icon will download the video in the chosen format (mp4/flv).