JimbeauC:
if you see the bar but nothing else when you hit the button then i would suggest you have some form of ad block in place
if playing but still "nothing", note that it often stops 1 second short and will need to be reloaded and watched again - this happens regularly and is almost certainly programmed to do so to force a second view.
edit - it took 2 reloads to get it to finish today, the usual joke.