An embed code provides HTML markup that makes it possible to stream a YouTube video on an external Web page. However, although individual YouTube videos can be embedded on other Web pages, so can ...

So it should use the HTML5 video if you have opted into YouTube's HTML5 trial. This will only be used for new articles, but I went ahead and re-published the article you linked.

Fullscreen APIs: The Fullscreen APIs in HTML5 mean YouTube can offer an immersive full-screen viewing experience with a standard HTML interface. Before this became available, a lot of extra code ...