Invisible buttons are created by filling in only the hit spot frame of the button. So, create a square of fill on the stage.
select it and hit F8. Select button from the list and give it a name for the library. I usually use “buttonBlank”. Double click on it to edit it in place. Grab frame one, and drag it to frame four. You should see the first three frames empty, and a filled key frame on frame 4.
Create the movie clip with this in mind.
The animation that you want to come into effect for each situation, should have a stop action on it’s first frame, and last frame, but you can do it all on the timeline for the movie clip. This way, when you call it to play it will goto where ever, start playing, and finish at a state that you’re comfortable with. The last frame of the rollout animation should have the following action
gotoAndStop(1);
sending the playhead back to the beginning.
Give the movie clip and instance name. Open the instance panel with menu option “window/panel/instance”. go to your main timeline and then select the movie clip. The instance panel will show you that it is a movie clip, and what it’s “library” name is. In the blank field, give it an instance name. We’ll use “myMovieClip” for this example.
right click on the button, and in the pull down menu that apears, select “action”. This will open the action panel.
click once in the scripting area, and paste the following code.
on(rollOver){
myMovieClip.gotoAndPlay(2); // play frame 2
}
on(rollOut){
//frame 11, being whereever your next segment of animation begins
myMovieClip.gotoAndPlay(11);
}
with the button inside the movie clip, you could illiminate the “myMovieClip” and just use
gotoAndPlay();
in those instances.
For reference.
The action panel will let you add script to three places in a movie.
A) Frame actions are created by clicking on a frame in the timeline and entering script into the action panel.
B) Movie clip actions can be placed on movie clips by selecting them, and then entering text into the action panel.
the have many formats but some of the more common are shown here
onClipEvent(load){}
onClipEvent(data){}
onClipEvent(enterFrame){}
C) Button actions are created by selecting a button, and entering script into the action panel.
they have many formates but some of the more common are shown here
on(release){}
on(dragOver){}
on(rollOver){}
on(rollOut){}
on(press){}
note: most common mistake: most often newbies make the mistake of thinking that they have a movie clip or a button selected when in fact they do not. Keeping the instance panel open during action script creation is vital for keeping track of exactly what you have selected. After all, a button can be inside a movie clip. That same movie clip can be inside a group, a graphic, or another movie clip. etc. The point is, it can often look like you’ve selected something, when in fact you have not. 
note:about invisible buttons: One of the beutiful things about flash is that it loves to reuse things. A button which is a square of fill, but has no visual attributes takes up about .1k. If you were to use the same invisible button from the library, everywhere in your movie that you had button interaction, it wouldn’t matter how many times you did, the user would still only have to download 1 .1k object.
You are welcome to scale each instance of the blankButton to your particular need. It will not effect how the button reads “on mouse” methods.