If a video or resource in Moodle displays as a blank page, this is likely because the browser is blocking the content. This happens because Moodle is a secure website. Browsers will assume certain types of content are malicious and will not display the content (e.g., scripts running from within a frame).
Displaying blocked content
Look for the shield icon on the left side of the URL bar. Click on it and select Disable protection for now from the Options menu, as shown in the image below. The page will reload, and the content should display appropriately.
Look for the shield icon on the right side of the URL bar. Click on it and select Load unsafe scripts, as shown in the screenshot below. The page will reload and the content should display appropriately.