Assigning _root variable from dynamic MC

Setup
I have mc that dynamically loads in a mc onto the stage. On the last frame of the dynamic mc it tells the main timeline to advance 2 frames which then load in the next mc.

Issue
Once all the mc’s play and the _root movie goes back to the first frame it still continues to loop.

Question
How do I assign a value to a var that lives on the main timeline from a dynamic mc that can also be read fromm the dynamic mc?

Here is my code:

 stop();
 ///////////////////////////////////////
 /////    Variable
 ///////////////////////////////////////
 var vid1;
 trace(vid1)
 vNav.gotoAndStop(1);
 loadMovie("media/vid1.swf", "vHolder"); 

here is the code from last frame of the Dynamically loaded MC:

 stop();
 // -----
 if (_root.vid1 == undefined){
 _root.gotoAndPlay(3);
 _root.vid1 = played;
 } else if(_root.vid1 == played){
     trace ("FOO")
 }