the problem is that the browser makers (google, microsoft, apple) use autoplay on their sites, so that they are not really interested in blocking it. you can try some extensions that block autoplay, some adblockers offer that feature too. firefox is also an option.
I set my browser's `content.autoplay` setting to `false`.
I stopped visiting sites with video autoplay.
I stopped visiting sites which lead me to site with video autoplay.