As soon as the extension is installed, you will be able to download a video right from the homepage. Click the "Download" button and choose one of available formats. Download and enjoy!

To do this, you need to download a free program called Ummy Video Downloader. Installation instructions can be found here.

After you have installed the extension, you will see a "Download" button under each video. Click it and select "HD via Ummy" or "MP3 via Ummy".

Attention! This method is only available to Windows XP/Vista/7/8 users.

While you are on YouTube.com just add "ss" to the video URL in order to start the default YouTube downloader. For instance:

Original URL: http://youtube.com/watch?v=YOcmSsBfafg

URL for downloading: http://ssyoutube.com/watch?v=YOcmSsBfafg