Editing Commercials out of VHS tapes while you are transfer to DVD Recorder. When commercial comes up press pause than pause again to start up your movie (this will put many thumbnails) as you are editing, once you finish with that movie. Check thumbnails, Give them titles, than Finalize your DVD and try it in a DVD player to confirm it works.
It's faster and easier to record to a DVD+RW disc, reauthor on your PC and then burn the finished product to a new DVD R (unless you have unlimited time to babysit your tapes).