There appears to be a mistake in the automaton diagram (not operation). The start state is "Idle, Up", and assumes the mouse is presently outside the button. But after doing "Click to Reset", you're already inside the button and so cannot enter it. Thus you should actually, and unfortunately, be in "Idle, Up". The demonstration gets around this by magically jumping to "hover", but this violates the whole educational point of what a start state is.
I know this is nitpicky, and yes, I see that "fire!" is an accepting state, but maybe you could have a special transition from "fire!" to "hover" labelled "reset".
1. You've made the unfounded leap that the diagram intends to represent state after the button has fired. That's manifestly incorrect.
2. You've made the incorrect assumption that a full reset of the diagram is accomplished by clicking the button. But that's not what it says. Obviously, you also need to move the mouse out of the button to return to the start state. So you could criticized this for incomplete instruction, however, since the context is a demo for a college course, omitting over-instruction of obvious and irrelevant details is most likely the best decision to reach the overall instructional goal.
If you want to be pedantic on the internet, you need to go a bit deeper than that. ;-)
Just think of it as throwing the old button away and buying a new one. Buttons come idle from the factory. Once the old button is hauled away and the new one is installed under where your cursor happens to be, it transitions to hover.
I know this is nitpicky, and yes, I see that "fire!" is an accepting state, but maybe you could have a special transition from "fire!" to "hover" labelled "reset".