Efforts are being made to prevent autoplay videos. Nextbigfuture is talking to the ad networks to prevent autoplays.
Click the menu icon on the upper-right corner and select Settings.
Then scroll down to the bottom of the page and click the Show advanced settings link.
Scroll down further until you find the Privacy section. Click the Content settings button.
In the resulting Content Settings dialog box, scroll down to the Plug-ins section. Select Click to play, then click the Done button in the lower-right corner.
Add Chrome Extension
Starting in Chrome 64, autoplay will be allowed when either the media won’t play sound, or the user has indicated an interest in the media. This will allow autoplay to occur when users want media to play, and respect users’ wishes when they don’t. These changes will also unify desktop and mobile web behavior, making web media development more predictable across platforms and browsers.
Not all users have the same preferences for autoplay media, so Chrome 63 will add a new user option to completely disable audio for individual sites. This site muting option will persist between browsing sessions, allowing users to customize when and where audio will play.