Paul –
Are they requesting something that will play in the Flash player or specifically requesting vector output in Flash format?
As mentioned above, the new On2 codec in Flash 8 is superb and you’ll get a FLV file which is Flashs video file format. Great quality considering the file size. Flash 8 comes with its own video encoder, and you can also get a On2 encoder from On2 directly or Sorenson that supports VBR and 2-pass encoding so you can squeeze every bit of quality out of your original quicktime file.
It was mentioned on PostForum that you could also use a frame-by-frame output and use something like Streamline or similar app to convert your bitmap into vector artwork that could be imported into Flash and would be vector. However, when I played with that method in the past, I didn’t get consistant results from frame-to-frame but it depends on your source. You could also import a bitmap sequence into Flash and convert it directly in Flash using its Trace Bitmap tool, but that would be a long process.
I guess it comes down to what your client really needs. If they need a Flash animation (all vector), then you could look at the process above or look at doing all the animation in Flash directly. Animating in Flash directly would give you the best results possible for a pure vector animation (small file size, better control). Although, it is possible to create a vector animation that has too many vector lines and actually bogs the Flash player. In my opinion, Erain’s Flash rendering engine does this and makes all but the simpliest animations too CPU hungry. If they just need an animation that can be played in the Flash browser plugin, then you have the FLV option as well. Flash FLV files are the Flash video format and can play back to version 7 of the Flash plugin (or v6 if its streamed from Flash media services).