OBS can be used to play a video element via a URL. Probably not what you want during a livestream where conserving bandwidth is paramount, but when you are pressed, this technique can be handy. Sort of. Note that even when the event is disabled the audio for the video will play when the scene is previewed. Not what you want during a performance.

document.getElementsByClassName('ytp-chrome-top')[0].style.visibility = 'hidden';
document.getElementsByClassName('ytp-chrome-controls')[0].style.visibility = 'hidden';
document.getElementsByClassName('ytp-gradient-top')[0].style.visibility = 'hidden';
document.getElementsByClassName('ytp-gradient-bottom')[0].style.visibility = 'hidden';
document.getElementsByClassName('ytp-progress-bar')[0].style.visibility = 'hidden';
document.getElementsByClassName('ytp-progress-bar-container')[0].style.visibility = 'hidden';

 

.ytp-chrome-top, .ytp-chrome-controls, .ytp-gradient-top, .ytp-gradient-bottom, .ytp-progress-bar, .ytp-progress-bar-container {display: none; }

 

<iframe src="https://www.youtube.com/embed/mqvQqqW8MQI?controls=0&autoplay=0" frameborder="0" width="1920" height="1080"></iframe>