If you want to target MC_3 as your empty movieClip that is in MC_2; from the timeline of MC_2, I would use:
MC_3.loadMovie("yourmovie.swf");
If you need to target it from somewhere else like the main stage, you must target everything in order for Flash to find it:
_root.MC_1.MC_2.MC_3.loadMovie("yourmovie.swf");
In the tools of your actions panel, there is a little crosshair target thing. If you push that when you are trying to target something, this will open up a pop up window showing you all your available targets.
I’m guessing you’ve gone through the kirupa loading external stuff tut. That’s the first step, understanding the loading - which I think you understand already. Then it’s experimentation (or at least that’s what it was for me).
I found this doing a search. Search for ‘targeting nested movieClips’. You’ll find some stuff:
- Targeting or referencing movieclips and variables is usually the hardest thing to come to grips with when using Flash. Because Flash supports nested timelines or really, nested movieclips, and each movieclip can contain their own set of variables, to correctly access specific movieclips and variables you need to be able to specifically target them. This is done through dot-syntax.