At 3:30 of the inset lesson, Mike says we cannot bring the edit box again, if we click away.
I don’t know if its only for newer blender version, but we actually can and its very useful to know.
If you accidentally click away and the box disappear, you can make it appear again by pressing F9.
Again, very useful to know 
Thank you for your observation.
It is partly true.
With f9 you can show the panel again, but not under all conditions.
Leaving and re-entering edit-mode.
Face selection … etc.
Well, I know the limitation of F9 and what it does…
I was mostly replying to the message said: “We cannot bring that back if we click away.”
We actually can, and I know you could just delete the geometry and add it again. But it is faster to just hit F9, specially if what you added was a complex spiral for example.
Well, some people don’t know about that. I didn’t even know about the F9 key so both your replies were very helpful to me. Thanks!
Welcome to this site.
Useful tips and suggestions as well as a place top show your work.
The f9 thing was relatively recently added it may well have been after the first part of the course was made. It is handy but you must not have done anything else at all since it was first given with the new mesh object.