JSFiddle - React, Tailwind, and code Playground
by Joshua Dwire
HTML
<div id="tester">Ac cursus? Amet rhoncus a, vut nascetur enim ut lorem nascetur ultricies urna, nisi tortor, augue, arcu nisi placerat nisi eu sociis diam augue dis a ridiculus vel, augue est. Habitasse auctor pulvinar dolor, ur[VIDEO]youtube.com/?avddee[/VIDEO]na! Ultricies! Ultrices adipiscing[VIDEO]youtube.com?/vvddee[/VIDEO] aliquet a? Velit ac, sed, a! Porttitor sagittis in est dictumst auctor.</div>
JavaScript
while(true){
var match = /\[VIDEO\]youtube.com\/(\w*)\[\/VIDEO\]/gm.exec(tester.innerHTML);
if(match==null)break;
tester.innerHTML=tester.innerHTML.replace(match[0],'<iframe width="420" height="315" src="http://www.youtube.com/embed/'+match[1]+'" frameborder="0" allowfullscreen></iframe>');
}