85% of people don't know this. In fact, I didn't even know it. So Bill Harris posted on the SEO Signals Lab Facebook group about video watch pages.
So if you get this error in Search Console, you'll be like, video isn't on a watch page. And in the comments, he explains you have to create a separate video watch page, which is a page with just the video and video schema markup on it. So a lot of you might create a page on your website where you've got the video embedded and then a bunch of text like a blog post or it'll be the transcript of the video.
You need to make two pages on your website. One is specifically a video watch page and it's just the video embedded and schema markup. If you have that, then you'll get this error out of Search Console and those pages will now be able to rank in Google's video results.