Can not hide the next button (38 sec) for my embeded and iframed youtube short video

You should use JavaScript to check if the video has ended rather than a timer. See this post:
https://community.qualtrics.com/XMcommunity/discussion/comment/54695#Comment_54695

Thank you TomG:-)
Do you mean adding this to JavaScript:
var tag = document.createElement('script');
tag.src = "https://www.youtube.com/iframe_api";
var firstScriptTag = document.getElementsByTagName('script')[0];
firstScriptTag.parentNode.insertBefore(tag, firstScriptTag);

var player;
function onYouTubeIframeAPIReady() {
 player = new YT.Player('myvideo', {
  events: {
'onReady': function(){ alert("here finally"); },
'onStateChange': onPlayerStateChange
}
});
}
function onPlayerStateChange(event)[
if(event data==YT.PlayerState.ENDED{
$('NextButton').click()
}
}

Yes, something like that. I didn't write that code and haven't tried it so I can't say for certain that it works. BTW, that code clicks the next button when the video has ended, which might not be exactly what you want.

Hi,
Thank you. That is precisely what I wanted, but I can not get it to work...