Where can I download Flash Movie Maker?

If you are talking about Macromedia flash, try purchasing it from their website - www.macromedia.com. It's not cheap, and if you are talking about an illegal version, we dont discuss warez on the boards.

There is also a much simpler flash designer called Swish if you don't have the time to learn the real thing. It can't do everything Flash can do, but it still makes Flash files with a lot of cool features.

Google it.