Here's the desired effect: a moth flapping it's wings and raising vertically at
the same time. I have the animation of the moth flapping it's wings, but how
do I make him rise? I guess I'm asking how to apply a motion tween to a video
(flash) clip.

Thanks for any suggestions.

Vince Vega huh?
Sounds kinda pulpy to me ,'8-)
But your question.
Always, always, always build your animations inside a movie clip, never on the
main timeline.
You can copy all the layers and frames into a movieclip so your still ok.
So, create a movieclip from your moth animation, then animate THAT vertically.
Or place the moth_mc inside another MC and animate the moth_mc there.
Then just drop the whole thing in a frame in the main timeline.
Depends on what your trying to do. But Named, Nested Movieclips is the way to
go.
See what I mean?
Jon