Without a lot more information from you it is very difficult for we fellow-users to offer any advice. Please read this post for details of what we really need to know. You haven't told us anything about your computer nor even the version of Rescue Your Videotapes you are running.
However, you mention that you are connecting your camera via the S-Video port. Are you also connecting the separate audio output from the camera to your computer? There must be one since the S-Video line will carry video only and always requires a separate audio connection.