Stop Youtube when changing between tabs (Quicktabs)
I think this post should help you: https://stackoverflow.com/questions/1094397/how-can-i-stop-a-video-with-javascript-in-youtube.

As @Pan Chrono said, it's not a drupal related question, more a youtube one.

What you basically need is:


change the way the youtube video is embed. It's actually using an iframe, you need a "embed" tag.
add "enable_js=1" to your URL so you can use Youtube Api
add a custom JS file to your page, and do some little jQuery code so that the video is stopped (with var myPlayer = document.getElementById('playerid'); myPlayer.stopVideo();) when you click on one of your tab