Storyline: Spot the Hazard Interactive Video

I like a lot, and I can see application in my line of work, but it seems that if you just click the button immediately, it thinks you have spotted the hazard...which you haven't. Any way round this?

I am thinking that the users cannot click until a hazard has been initiated, so in the case of the door opening, the "well done" should not become active until the door starts to open.

Many thanks for a great idea :)