Webinar - waiting room video didn't play

Hello all! 

We had a webinar yesterday and we set up a waiting room video. But it didn't play. There must be some setting that we are missing. We couldn't find an area to set up a time for it to play. So we assumed that it would autoplay. But it did not. Here's a screen grab. If I click on the three dots to the right (do we call it an ellipses or kebab??), nothing happens. And I am an admin.

Thank you!