Question: Nothing will play in my video stream!
Answer: If the bar at the bottom of the video-streaming client says 'Off Air', then you will not see anything because there is no video coming from the other end. If you don't see 'Off Air', click the circular-arrow refresh button on the bottom right of the video-streaming client, next to the full-screen rectangle button. Give the client up to 30 seconds to re-load.
Question: What if reloading the client doesn't work?
Answer: If nothing is playing still, refresh your web browser. If you're on a PC, hit Ctrl-R. If you're on a Mac, hit Cmd-R. Wait for the page to load up again, and click the big triangular "Play" button.