Sorry to hear about it and for not helping you sooner.
Did you see an error message? Is it a video and audio template? What is the length of the video? Could you download it on your device? Did you try using another browser to see if that would help?
Closing the tab and clearing the caches may help. You can log out, log in to your session, and try to play the video.
Can you share the video with us? It will help us to understand what you're experiencing.