BB FlashBack has an Optimise function that can be used to reduce the size of the FBR movie file as well as the SWF, Powerpoint and EXE export sizes. The size of the reduction will vary depending on the content of the movie.
How to optimise a movie:
In Player, select the Optimise movie item from the Tools menu.
The optimise process will run, and may take a few seconds to a few minutes, depending on the size of your movie.