For interactions that doesn’t pause the video, the interaction buttons is displayed several seconds after the interaction is done/closed. A couple of times I opened the same interaction again, only to find out I had already solved it. I think it should be hidden after it is closed. This could be implemented as a setting (eg: “Hide after clicking continue”). Another solution could be to do something visual with it to indicate it has been done/opened.
Users should understand which interactions have been completed