Another option would be to use BitmapData class. although this is very very slow it will do what you need to as well.
I can tell you what it should do, but if it doesn't I can't fix it for you, I don't use it...
It should go pixel by pixel in the mc stated and get the information, then in turn changing it to a bitmap file then you can do what you need to with it. It works but is SUPER slow. The idea being you are selecting a certain MC, if you want the whole stage make a holderMC and do the whole stage inside the blank MC. Code the BitmapData to the holderMC and viola a stage screen shot