How do I use a rotary cutter? Cutting fabric for dummies

I was going to get myself one of these, but thinking twice about how many times I burn or cut myself when doing things, I thought maybe better not.
I think one of these would slice your finger right off?

I kept this great tutorial for when I got one.

THE PURL BEE ROTARY CUTTING TUTORIAL

It's like a cutting for dummies :)