It's working for me -- I'm on Chrome 106 on Mac (M1) and the example reports "hvc1" as it's playing.

You might have an older Mac without the necessary hardware decoder.

The article mentions a caveat:

> HEVC is only supported if the underlying device has an HEVC hardware decoder.

Does your computer have hardware HEVC decode?

That's why Firefox don't want to support it. Because you can only provide hardware decode unless you pay huge amounts of license fees to the license leeches. Which will make this format only works on some devices but not others.

The h264 has a free software decoder so your browser can play it no matter your device supports it or not