music not stopping on video when back button is pressed

Hi I have a video on a scene

The video is on its own scene. The video is of file format .mp4 file format. When I import the video to flash a dialogue box loads Select Video

Where is your video file?

On your computer.

I select radio button load external video with playback components.

The video has sound on it. On this scene I have added a back button that takes the user to a navigation scene. When the user clicks on the back button the music continues to play. How can I get the video to stop playing when I press the back button.

I am using actions script 3 code. This is the code for the button.

stop();

import flash.events.MouseEvent;

bkbtn.addEventListener(MouseEvent.CLICK, backbtnEvent);

function backbtnEvent(evt:MouseEvent):void

{

            gotoAndPlay(1,"Navigation");

}