How to download YouTube audio and video

A friend asked me to show them how to download YouTube audio and video files. The Firefox browser has dozens of addons to do this. Two I have used and recommend are:

For Audio only-Youtube MP3 Podcaster
It puts a red icon on your toolbar. It allows you to save either the file in FLV, MP4, or MP3 audio formats. Save the file to your music folder.

https://addons.mozilla.org/en-US/firefox/addon/youtube-mp3-podcaster/




For Video and audio-Flash Video Downloader
Use the MP4 format. It is smaller and will take less time downloading, and has excellent quality.

 
 
https://addons.mozilla.org/en-us/firefox/addon/flash-video-downloader-youtube/