I have an embedded mpeg as my very bottom layer, what i want
to do is have a section of a shape go behind an object in the mpeg
when it moves so that the shape appears behind the movie object.
How do i go about doing this?
Is the object animating? If so, the best way is to do the
composition outside of Flash and include it in the video.
Otherwise, yes, masking is your best bet (probably, without
seeing the video). You would probably have to create a frame by
frame mask if the object is moving. I'm also not sure it will be
possible to synchronize the stage animation to the video animation,
but it might be since it's embedded.