Events for both hotspot clicks and clicks on buttons and overlay elements in interactive videos are surfaced in the Vimeo Player API (see documentation). (Note: Interactive requires a custom Enterprise account).
By listening to these interactive events, you can create integrations between the interactive video and your parent page. For example, adding a product to a cart on the parent page where the video is embedded.
You can also insert custom data into the payload inside the interactive editor when creating a hotspot or an element in an overlay (for example, a product SKU) which will help your developers better utilize the events in their scripts.