How to specify javascript to run when ModalPopupExtender is shown

function pageLoad(){    var popup = $find('ModalPopupClientID');    popup.add_shown(SetFocus);}function SetFocus(){    $get('TriggerClientId').focus();}

function pageLoad() {
    $find('mpeBID').add_shown(HideMediaPlayer);
}

function HideMediaPlayer() {
    var divMovie = $get('<%=divMovie.ClientID%>');
    divMovie.style.display = "none";
}