Denon DVD-9000 Operating Lnstructions page 51

During playback, press the A-B button
e This sets start point A.
Press the A-B button again.
e This sets end point B, and repeat playback of the A-B section
starts.
* To return to normal playback:
Press the A-B button until "A TO B CANCELLED" appears on the TV screen.
@ Repeat playback may not work for some DVDs.
0 The repeat playback and A-B repeat playback functions will not work for DVDs and video CDs for which the elapsed time is not
shown on the display during playback.
e In some cases, subtitles may not be displayed near the A and B points during A-B repeat playback.