Try the following steps to troubleshoot why a PowerPoint presentation is not playing an online video:

1. Ensure the video is embeded in the presentation and not just linked.


2. Confirm the internet connection is active and running at full speed.


3. Restart the application or computer.


4. Check if the video is playing in a browser outside of the application.


5. Make sure the video player is up to date and supported.


6. Re-link the video to ensure the URL is correct.


7. Re-embed the video into the presentation.