So I am working on an interactive piece that requires the use of pre rendered 3D animation clips with transparency. what I was curious about is... Would it be better to export the video as a series of PNGs (the longest is about 600 frames long) and import those into my movie clip or should I export the video as an FLV that is close to 400 Mb in size? Or am I completely missing a a better way to get this pre-rendered animation into my piece as a clickable movie cllip with transparency? Thanks.
I would try the flv conversion first and see if the flt streams well. That way the weight of the Flash file doesn't suffer like it will with potentially thoudands of png images being imported into a movieclip.
You will have to export flv with alpha channel (http://www.leebrimelow.com/?p=59). Then you should import the flv into *.fla (as MovieClip import option). The interactivity is the tricky part, though. Transparent video, as well as transparent PNGs is a big rectangle and even the transparent part of it clicks. You can create hitAreas - transparent vector fill. Inside the MovieClip with the video, draw any vector shape with transparent fill. Convert it to MovieClip and set it as the video MovieClip's hitArea, or just add click listeners to it.