First time for me that swirly thing was distracting my attention and I was doing rapid saccades looking for weird hidden items (even though I knew that was prob

First time for me that swirly thing was distracting my attention and I was doing rapid saccades looking for weird hidden items (even though I knew that was probably part of the illusion, seemed best to play along). I didn’t notice a single thing changing so the illusion worked perfectly for me. Second time watching it was easy to see the changes.