It sounds like you are using the
tools-> MPEG encoder. If you just want a series of JPG's on a CD/DVD you should try the
Album -> Archive To CD option. If the photos aren't already in jpg format you can use the
Tools -> batch -> convert images
if the above suggestions do not help you can try the digikam handbook at:
http://www.digikam.org/handbooks/en/index.html
If you have recorded a video with the camera and want to turn that into a series of jpegs then you probably need to use something like ffmpeg or mencoder.
Hope this helps
Freemor