In Google's Search Console, you will see Video Pages on the left menu under Indexing. If you go into Video Pages and see the error "Video is not the main content of the page" similar to the screenshot below.
In this specfic example, the website is using a video as a background that automatically plays on the page load. The original code that was causing an error in Google was <source src="https://media.cmsmax.com/2ytswhs6rbgunou9qv1so/monroe-flooring-splash-video.mp4" type="video/mp4"></video>. To fix this error, we have updated the code to be INSERT HERE
This report shows the validity of structured data items that define videos. To see which videos were indexed, and reasons for not indexing, visit Indexing > Video indexing. Learn More
