You got several options here what should happen if the file rescue finished. This is helpful if you have many different medias to rescue files from and don't want to sit on the PC looking for the progress all the time. When the rescue finished you get notified by sound and the CD/DVD drive opens if you want to.
Play Sound (Soundcard)
Useful if your Monitor or Boxes are on so that you hear a signal.
Play Sound (PC-Speaker)
Useful if you have no Soundcard at all or don't have the Monitor on.
Open CD/DVD if possible
In case you rescue files from optical media it is helpful to see the drive getting opened when all is done so you can simply insert a new media and close it to continue automatically.