If you have to explain a concept to someone you better make sure to match their proficiency level so that they actually understand what you are talking about. If you work in tech support you usually talk to users all the time who have little to no knowledge at all about technology. They might get confused if you throw words like web browser, email client or operating system at them.
In Plain English is a video series on Youtube and the common craft website that explains concepts in plain terms so that everyone, even someone who has little to no knowledge about the concept can understand it.
Their latest video is for example explaining RSS Feeds. How would you explain RSS feeds to someone who never heard about the concept before. The videos do an excellent job of explaining these concepts in plain terms. There are basically four topics (Green, Money, Society and Technology) to chose from. The technology category contains explanations of Twitter, social media or wikis among others.
All videos are made without computers and do not show a single computer screen or hardware. You can watch all videos either on the Common Craft website or at Youtube directly.

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They are also available at http://vimeo.com/ and http://dotsub.com/
dotsub videos shows up legends in some languagues including brazilian portuguese.
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Luciano Evaristo Guerche (Gorše)
Taboão da Serra, SP, Brazil
To go straight to the videos, the URLs are http://vimeo.com/user230075 and http://dotsub.com/view/user/leelefever
Very cool, Martin. Thanks for sharing this.