>WebKit in Safari now supports loading H.264 encoded MP4 video with an HTML tag.
I was confused by this sentence, but it actually says "HTML <IMG> tag" (the "<IMG>" part of the text is unescaped, and does not render). Meaning you can use <img src="video.mp4">
"But we already have <video> and animated webP and..." is addresed in depth in the linked article: https://calendar.perfplanet.com/2017/animated-gif-without-th...