JSFiddle - React, Tailwind, and code Playground

HTML

<div class="content"><p>Here is a cool video.  Check it out: http://www.youtube.com/watch?v=oHg5SJYRHA0 and this one http://www.youtube.com/watch?v=fLBPsZVI8Gc&feature=player_embedded</p></div>

<br>

<div class="content"><p>Here is a cool video.  Check it out: http://www.youtube.com/watch?v=fLBPsZVI8Gc&feature=player_embedded</p></div>

JavaScript

$(document).ready(function(){
 // I added the video size here in case you wanted to modify it more easily
 var vidWidth = 425;
 var vidHeight = 344;

 var obj = '<object width="' + vidWidth + '" height="' + vidHeight + '">' +
     '<param name="movie" value="http://www.youtube.com/v/[vid]&hl=en&fs=1">' +
     '</param><param name="allowFullScreen" value="true"></param><param ' +
     'name="allowscriptaccess" value="always"></param><em' +
     'bed src="http://www.youtube.com/v/[vid]&hl=en&fs=1" ' +
     'type="application/x-shockwave-flash" allowscriptaccess="always" ' +
     'allowfullscreen="true" width="' + vidWidth + '" ' + 'height="' +
     vidHeight + '"></embed></object> ';

 $('.content:contains("youtube.com/watch")').each(function(){
  var that = $(this);
  var vid = that.html().match(/(?:v=)([\w\-]+)/g); // end up with v=oHg5SJYRHA0
  if (vid.length) {
   $.each(vid, function(i){
    that.append( obj.replace(/\[vid\]/g, this.replace('v=','')) );
   });
  }
 });
});