hmmm...don't know...what does "jump-back" do?

I think he means where a recorded show is say an hour long. There are 4 15 minute partions (TiVo breaks all recordings into 15 minute partitions on the time bar.) You can hit FF or REW then hit the skip button and will immediately go to (or "jump-back to" ) the next bar instead of waiting for the FF or REW to get to that point. It's good for skipping through movies or other long shows to get near a point in the recording. At least mine works that way (DirecTiVo) but I enable the 30 second skip backdoor on mine. I'm not sure if that changes the function of the jump back feature