How to stop video player in Blackberry?

Question

Hi,

I created one blackberry application which will play a video on a button click.This is my code,

    invocation=new Invocation("file:///SDCard/Blackberry/videos/PlayingVideo/funny.mp4");       
    registry=Registry.getRegistry("net.rim.device.api.content.BlackBerryContentHandler");           
    try
    {               
           registry.invoke(invocation);             
    }
    catch(Exception e)
    {
    }

Now i can play the Video file.After clicking the Back button the native player is going to the background.It always running in the background.But i want to close that player.I have no idea about how to do it.Anybody knows please help me.