[AS2] Bug in CS3 / CS4?

Dear all

I have a single movie clip which has an embedded video inside. I use the following actionscript commands to stop and play it
onClipEvent(load) {
stop();

onClipEvent(mouseDown) {
play(); }
onClipEvent(mouseUp) {
stop(); }
}

The problem I face is that the movie clip should play when clicked by mouse ONLY on movie clip area which occupies only a small part of the stage. However, when I click the mouse ANYWHERE on the stage the movie starts to play.

This seems to be a bug in Flash CS3 / CS4 ? Any help ?