For Firefox: About:Config setting media.autoplay.enabled to false.

For Chrome: Chrome://flags set autoplay policy to "Document user activation is required".

I know that this breaks animated .gifs in Firefox, though you can get them to animate by viewing the image info (right-click menu). That's rarely a big loss anyway.

With uMatrix I was able to read the article without loading any of the external cruft, it does add some cognitive overhead to browsing sites with a lot of external dependencies