For non-mathematicians who are interested in the math of epidemics

I found this video:

It's nine minutes long, but it's good, so the time flies!

The creator is a mathematician, not an epidemiologist or public health or infectious disease expert, so he acknowledges that he can't account for reinfection or the possible number of unreported cases. But it's a neat explanation of how big a difference little changes can make (e.g., if everybody starts really washing their hands), so while it's a little scary, it's also encouraging.