As I was watching the part about setting up the OnDrawGizmos method I was wondering why someone would do that instead of just assigning an icon to the empty game object from the little cube shape in the inspector.
The longer bars even show the objects name.
I would guess they had the OnDrawGizmos part in there so that we could learn what it does but maybe it could have been saved for a later course when it may have been more helpful. For example, I watched a friend use it to show the range of an enemies attack.