reveal video in carousel breaks autoplay when page has been prerendered

[kapouer]

See e.g. https://groupe-dfm2.pageboard.io/

[jsbastien]

This used to work all right. (Translated for forward readability).

[kapouer]

Not a bug !

Autoplay policy is the culprit here: https://www.blog.google/products/chrome/improving-autoplay-chrome/

Summary:

• if the user interacted with the page, autoplay works
• else the video has to be muted for it to always work
• if the user often plays videos, the website is whitelisted and autoplay will work (for that user)
• if we're making the next youtube, it will become eventually whitelisted by default