Use HTML elements commonly used for embedding videos. “Don’t use fragment identifiers to load the video, as Google Search doesn’t generally support URL fragments.” If JavaScript injects the video, check that it appears in the rendered HTML in the URL Inspection tool. Don’t rely on user actions such as swiping, clicking or typing to load the video.
Officially documented · Google Search Central
Metadata helps: Google supports structured data (VideoObject), video sitemaps and the Open Graph protocol.
The watch page must be indexed, and it must perform well in Search before its video can be considered for indexing. Even then, “Just because the watch page is indexed doesn’t mean that the video will also be indexed.” The video can’t be hidden behind other elements. It needs a valid thumbnail available at a stable URL.
Officially documented · Google Search Central
“Some CDNs use quickly expiring URLs. If the video’s thumbnail URL changes too often, Google may not be able to successfully index your videos.” Data URLs aren’t supported.
Officially documented · Google Search Central
“A watch page’s main purpose is to show users a single video.” A video landing page or a TV episode player page counts as one. A blog post reviewing an embedded video does not, and neither does a product page with a 360 video of a product. In those cases the video is complementary to the rest of the page.
Officially documented · Google Search Central
URL Inspection reports “Video isn’t on a watch page” when the video is supplementary to the textual content. It also notes that only one video can be indexed per watch page.
Officially documented · Google Search Console Help
Give each watch page a title and description unique to its video (Title links and snippets ).