The full video is a little better because it shows it happen twice, which affirms that drawing a sprial really does make that cat dizzy enough to fall over.
Pretty sure that cat got a contact buzz from the Sharpe there. Their noses and skull make up allow for toxins to transfer to their brain rather quickly. Same reason they go nuts when they lick ice cream - the effect hits very quickly.
Based on everything there, the movement kept the cat interested & eventually the fumes put it in a vertigo state, it got dizzy & down the cat went. :)
