Using a bookmarklet is the fastest and easiest way to download a YouTube Video. Here’s a working bookmarklet to download YouTube videos in MP4, FLV and HD format.

Just drag [PwnYouTube] bookmarklet in the bookmarks bar of your browser. Then open the YouTube video you want to download and click on the bookmarklet. You will see a pop up yellow bar instantly. Click on the links on this bar to download the video in desired format.