Just caught this...
that's a serious problem. Much as you might not want to do it, I think you need to create a load structure that will load and parse the PNG files on the fly on an as-needed basis. It doesn't make sense to preload a bunch of FLVs and extract snippets from them, nor do I think it's possible. There are a couple other options, though it might be too late for them; but if you're willing to restructure a little bit, I would definitely suggest you create sprite sheets for each animated character and put them into one or more .swfs in the library, then load them on call, and create a simple class that masks them out and moves the underlying sheet to the coordinates that were called for; you could even use one sprite sheet for multiple animated characters if you're clever about how you lay them out.
If you don't know what I mean by a sprite sheet, this is a sprite sheet of Barney the Purple Dinosaur:
http://sousanator.psparchive.de/Spri...ets/barney.PNG
This is the way game designers have been doing animated characters since time immemorial and although there aren't a lot of flash coders who do things this way, there also aren't a lot who do big games with lots of 2D characters...