All teachers teaching technologically orientated students know the outstanding site called "how stuff works". Do you know that they recently added a video section? Of course, at the moment, there are no scripts, but if the students have learnt enough about the topic through the written pages of the site, they will understand the video.
This week's video is about recycling mobile phones, and you can also read pages about what's inside a mobile phone and how it works.
Last week's video was about how drawbridges work, and there are many other.