Lisa,
You won't be able to address duration settings in Captivate;
all that Presenter "sees" is a self-running swf file, so as
catholicon mentions, Presenter 7 interprets the duration of the
imported swf.
That assumes, however, that you have Presenter 7. One other
thing to check (if you've got any of the earlier versions of
Presenter), is the setting for the slide itself (meaning, the slide
that your Captivate movie appears on).
In earlier versions of Presenter, you have the option to edit
the Slide Properties of a given slide. Enabling "Advance by User"
will force the slide to pause even after the default of 5 seconds,
so that it won't automatically advance by itself. Again, I'm not
sure what version of Presenter you have, but that might be one
other thing to check.
Rob