A video on your webpage does not display and the console shows an error about mixed content. What is happening?
Your browser does not support HTML5 video.
The page is loaded via HTTPS, but the video is being served insecurely as HTTP and the browser is blocking it.
The webapge is using a DOCTYPE, which renders it incapable of displayed video in addition to other web content.
The video is from a source that cannot be displayed in your location for legal reasons.