mouse up on stage and buttons AS2

I have a presentation that uses the following to play timeline when mouse is clicked (anywhere on screen)

onMouseUp = function ()

{

play();

        onMouseUp = null(); //cancels function after click

}

However i have added a YouTube video and a "click here to play" video button but when i click it runs the MouseUp function and continues the presentation and doesn't play the video pop up.

How can i tell flash that if i click the button not to perform the standard onMouseUp function ???? while still keeping that function available for the user to continue the presentation?

Thanks