An article I read on Plasma commented on this issue that sometimes outputting to a video format can yield better results (both quality and size) then using a flash vector output program. If you want to incorporate the movie into a larger Flash piece (especially one targeted at player versions below 6), though, it still may be more helpful to have a .swf than a .mov or .avi A product called optimaze is supposed to help make flash movies smaller but I haven't been able to find a demo version.