How disable checkbox when listbox value changes in tinymce

Looking though the existing plugins, the standard tinymce way to do this is to save the popup window in a win variable:

{
    text: 'Vídeos',
        onclick: function() {       
            var win = editor.windowManager.open({ //etc

And then use win.find('#name') to target the control, eg:

{type: 'listbox',   
name: 'video_site',
onselect: function( ) {
    var autoplay = win.find('#video_autoplay');
    if (this.value() == 'vine') {
        autoplay.disabled(true);
        autoplay.value('');
    } else {
        autoplay.disabled(false);
    }
},