Add this code to make the thumbnail or link text to be the action of the popup
<a data-target="#video-modal" data-toggle="modal" href="#"><img class="img-responsive" src="SOURCE" /> </a>
Add this code to the bottom of the source code
<div aria-labelledby="myModalLabel" class="modal youtube-video-modal video-modal fade" id="video-modal" role="dialog" tabindex="-1">
<div class="modal-dialog modal-lg" role="document">
<div class="modal-content"><button aria-label="Close" class="close" data-dismiss="modal" type="button"><span aria-hidden="true">×</span></button>
<div class="modal-body">
<div class="embed-responsive embed-responsive-16by9"><iframe allowfullscreen="" frameborder="0" height="315" src="YOUTUBE URL HERE" width="560"></iframe></div>
</div>
</div>
</div>
</div>
