Question

Trying to add a border to the thumbnail video that’s playing in the iframe.

$('document').ready(function(){

    $("#video-thumbs li").click(function(e){
        e.preventDefault();
        $("#video-thumbs li").addClass("current").not(this).removeClass("current");
      });

});

<iframe width="1020" height="574" id="myvideo" src="http://www.youtube.com/embed/Qdse1SEBimw" frameborder="0" allowfullscreen=""></iframe>
<ul id="video-thumbs">
    <li class="current" style="margin-left: 0;">
    <div id="playbtn" onclick="document.getElementById('myvideo').src='http://www.youtube.com/embed/Qdse1SEBimw'"></div>
    <img src="files/lamb.png" width="326" height="181">
    </li>
    <li>
    <div id="playbtn" onclick="document.getElementById('myvideo').src='http://www.youtube.com/embed/WZknytdWWhI'"></div>
    <img src="files/tuna.png" style="width: 326px">
    </li>
    <li style="margin: 0 0 0 11px">
    <div id="playbtn" onclick="document.getElementById('myvideo').src='http://www.youtube.com/embed/BAembvTjChs'"></div>
    <img src="files/myers.png" width="326" height="181">
    </li>
</ul>

Answer 1

Try structuring the HTML differently, and remove those unsigthly onclick functions :

<iframe width="1020" height="574" id="myvideo" src="http://www.youtube.com/embed/Qdse1SEBimw" frameborder="0" allowfullscreen=""></iframe>
<ul id="video-thumbs">
    <li style="margin-left: 0;">
        <div class="playbtn" data-url='http://www.youtube.com/embed/Qdse1SEBimw'></div>
        <img src="files/lamb.png" width="326" height="181" class="current">
    </li>
    <li>
        <div class="playbtn" data-url='http://www.youtube.com/embed/WZknytdWWhI'></div>
        <img src="files/tuna.png" style="width: 326px">
    </li>
    <li style="margin: 0 0 0 11px">
        <div class="playbtn" data-url='http://www.youtube.com/embed/BAembvTjChs'></div>
        <img src="files/myers.png" width="326" height="181">
    </li>
</ul>​​​​​​​​​

Now do some jQuery stuff :

$(function(){
    $("#video-thumbs li").on('click', function(){
        $(this).find('img').addClass("current").end()
               .siblings().find('img').removeClass("current");
        $("#myvideo").prop('src', $(this).find('div').data('url'));
    });
});​

And it should work fine ?
Here’s a FIDDLE