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.

The solution is HTML5 video, but that relatively young technology requires further development to meet the needs — and DRM requirements — of a service like Netflix. According to the blog post ...

However, HTML5 Reset has a very nifty class for clearing floats without extra markup, so I ended up incorporating that element into my own Sass-based boilerplate code.

By switching to HTML5, YouTube can now also make wider use of Google’s VP9 video codec. YouTube says this switch allows videos to start 15 to 80 percent faster and reduces the average bandwidth ...