Get step-by-step instructions for adding YouTube clips to your digital media projects: Digital Media Life Hacks-YouTube Clips
YTD Downloader: allows you to download videos from sites like YouTube and Vimeo. Warning: When downloading this software "the installer includes a Spigot-based YTD Video Toolbar and offers to change your default search engine to Yahoo and add 5-6 shopping extensions to Google Chrome. Clicking the "Decline" button during the lone advertising screen in the installer lets users easily opt-out of all offers.-- CNET"
You can also download YouTube videos using a browser app/add-on in Firefox and Safari. Access these programs from your brower add-on option.
Examples of Firefox YouTube downloaders.