Comment by lifthrasiir

That is not correct. The surrounding code gives some more context:

    h=document.createElement("video");l=new Blob([new Uint8Array([/* snip */])],{type:"video/webm"});
    h.src=lc(Mia(l));h.ontimeupdate=function(){c();a.resolve(0)};
    e.appendChild(h);h.classList.add("html5-main-video");setTimeout(function(){e.classList.add("ad-interrupting")},200);
    setTimeout(function(){c();a.resolve(1)},5E3);
    return m.return(a.promise)})}

As far as I understand, this code is a part of the anti-adblocker code that (slowly) constructs an HTML fragment such as `<div class="ad-interrupting"><video src="blob:https://www.youtube.com/..." class="html5-main-video"></video></div>`. It will detect the adblocker once `ontimeupdate` event didn't fire for 5 full seconds (the embedded webm file itself is 3 seconds long), which is the actual goal for this particular code. I do agree that the anti-adblocker attempt itself is still annoying.