Newbie: some viewers don't see my movie in web page

I apologize for how basic this probably will be. I have very little experience
with Flash. I converted a Quicktime video with the Flash CS3 Video Encoder,
imported it into a Flash file (Flash CS3), put in on a web page just to share
with my family a little video of my grandson. On my Safari and Firefox (Mac)
they work fine, and from the web, not just the files on my own disk. But
others in my family don't see the video.

I wondered if maybe they don't have a recent enough version of Flash Player,
but my brother has a virtually identical computer and Safari, and at my request
he checked and he has Flash Player 9.

Would any of you be willing to look at this page and see if you can tell what
I've done wrong?

http://www.theophan.net/video/nemo.html

Many thanks!

Charles