I am not sure that I fully understand what you are referring
to when you say that you cannot capture more than 3 seconds. It
does not sound like you are referring to using the Full Motion
Capture option (F9/F10), but yet you are expecting a recording like
that in which everything on screen is captured while capture is
running. Captivate does not record in real time unless Full Motion
has been activated and even that is only designed for short periods
such as capturing a drag and drop action or scrolling. The standard
capture is for Captivate to grab a screen capture when an event is
triggered such as clicking a button on screen with the mouse. This
will tell Captivate to take a screen capture and when you are done,
it will extrapolate the position of the cursor from one screen to
the next to determine the mouse path.
The timing of a slide itself is defaulted to 3 seconds, but
can be changed. This has no bearing on the original capture though;
it has more to do with the length of time the slide will display in
playback mode.