Another possibility is to add a variable onto the flash movie name in the object tags like this :
<param name="movie" value="diapo2.swf?flashVar=open" />
- you need to do it to both instances of the swf name
when the page loads the swf picks up the variable and it becomes available to the movie in the root or level0 if you prefer
then you just need to detect the value of the var and tell the movie timeline to go to any place in the movie you want
if you have a different var in each page you can show a different part of the movie each time