var thumbs = YAHOO.util.Dom.getElementsByClassName( 'thumb', 'img' );
var vids = YAHOO.util.Dom.getElementsByClassName( 'vid', 'div' );

function activateTab( e ) {
   //alert( this.title );
   for( i = 0; i < vids.length; i++ ) {
      vids[i].style.display = 'none';
      //tabs[i].className= 'tab inactive';
   }
   curr = document.getElementById( this.title );
   curr.style.display = 'block';
   //this.className = 'tab active';
}

YAHOO.util.Event.addListener( thumbs, 'click', activateTab );