Thanks for the question. Magic is intensified on every revealed story space without a Fable on it -- on both sides of the story board.
As you note from the example, the left board had Fables on each revealed space so that's why we only show intensification on the right board.
During Action 8: Intensify Magic do you add a Magic token to each Story Space that doesn't currently have a Fable on both sides of the Story Board or only on the right side (non Book of Tales side) of the Story Board?
I ask because the different examples in the rule book and the instructional video show Magic tokens being added to only the right side of the Story Board during Intensify Magic. However, I did note that in both examples there were Fables on each revealed space on the left side of the Story Board.