I’ve found that in Chrome 66 (macOS), the embedded video player is blocked from playing when the user clicks the Play button. You can make it play if you click two more times.
The console logs an error when you click the Play button:
Uncaught (in promise) DOMException: play() failed because the user didn't interact with the document first. https://goo.gl/xX8pDD
Stack trace came from this script:
Here is an embed code that demonstrates the bug:
<blockquote class="twitter-tweet"> <a href="https://twitter.com/Cmdr_Hadfield/status/988788282396835842"></a> </blockquote> <script async src="https://platform.twitter.com/widgets.js"></script>