K weight & complex rollover btns

Using a complex button that uses nested MCs as more of a menu that also includes additional content that only displays on rollover from Kirupa’s tute

stop(); // stop the movie clip from playing (stop button from growing, we want that when the mouse rolls over only
this.onEnterFrame = function(){
 if(rewind == true){   //if rewind switch is set to true play backwards
  prevFrame();        // play backwards
this.onRollOver = function(){
 rewind = false; //set variable (or switch) that decides wether or not to play backwards...
 play();    // play this movie clip.. (grow the button(tween));
this.onRollOut = function(){
 rewind = true;    //set or rewind switch to true so it will play backwards...

Am I correct in thinking that the additional content does not load until encountered and technically the k weight of each of these nested MCs does not influence how long it takes this SWF to be ready to play.

I am very k weight conscious & this is something I have always wondered about.