Stop video player

i have a stop command on my actions layer at frame 20. There is a button on the stage that will go to frame 21 and contnue playing the timeline when pressed. I want my video which starts on frame 1 to stop once the go to frame 21 button has been pressed. Currently when the button is pressed, the video continues to play.
What code do i need and where do I put it, in the player layer, or the button layer? I hope this is clear.
here is the code for the player layer:

var videoConnection:NetConnection = new NetConnection();
var videoStream:NetStream = new NetStream(videoConnection);“”);
var metaListener:Object = new Object();
metaListener.onMetaData =onMetaData;
videoStream.client = metaListener;
var video:Video = new Video();
video.y = 70;
video.x = 440;

function onMetaData(data:Object):void
play_btn.addEventListener(MouseEvent.CLICK, playMovie);
stop_btn.addEventListener(MouseEvent.CLICK, stopMovie);

function playMovie(event:MouseEvent):void


function stopMovie(event:MouseEvent):void

Here is the code from the button layer:
hor.addEventListener(MouseEvent.CLICK, goForward);
hor.buttonMode = true;

function goForward(event:MouseEvent):void {
gotoAndPlay(hor.currentFrame + 21);