Bill Hammack, known on Youtube as the Engineer Guy, is one of the best Youtube channels which I subscribe to. I would consider myself a layman in the engineering field, but in watching his videos, I have learned more about the technology I use daily.
In his videos he not only talks about the subject he's covering, but sets up demonstrations as well. In his fiber optics video, he modified a bucket with a viewing window on one side, and a hole with a stopper on the other. By shining a laser through the viewing window and into the stream he had created, he showed how light interacts within a fiber optic cable. In this way, he makes his videos both informative and interesting, and because he uses visual props, it's much easier for me to understand just what he's talking about.
The video below is about smoke detectors, and I chose to share this one because I was surprised at the level of sophistication which goes into their design.
If you missed the links above, his website is here, and his Youtube channel is here.