I think the only thing I would change is explaining what miners do. "Solving complex math problems" is one of those phrases that people have latched onto, but I think it's a distortion. They really aren't "solving" anything more than they are tweaking some parameters to a mathematic operation, running the operation, and doing that until the result is a number lower than an improbable target. It is almost like gambling, but they've outsourced the rolling of the dice to dedicated dice-rolling machines.