* One doesn't have to be a master to make a learning tool.
Here is a potential interactive learning tool to teach how gears work and their relation to ratios.
Users might be be able to select how many keyed shafts to use. Next, they could stack different gears on the shafts. Finally, the program could spin the gears for us see how they would move. I don't have to be a mechanical engineer or master mathematician to see this. A similar concept would apply to the pulley.
* YouTube and other videos are a lecture with distracting video. Listening to others talk is not how most people learn the easiest. Videos are common because they are easy to make, not because they are superior at helping the viewer learn.
* Interactive learning activities is somewhat new. Does this explain why this thread isn't getting any good feedback?