Riplock is a term used for locking the reading speed on a drive for certain media types. For example a DVD-VIDEO will only read back at a certain speed, somewhere around 4X - 5X. This keeps the film makers happy as you wonâ€™t be able to backup a DVD very quickly. Another use for riplock is keeping noise levels down when playing back a DVD movie on your PC.
In most patched firmwares riplock has been removed, allowing faster rip speeds, these will generally only affect pressed DVD discs. For DVD5 (SL) the drive will generally reach its max read speed with riplock removed. For DVD9 (DL) the rip speed will be much reduced. In the case of the ND-3500 series drives, about 7X is all you should expect.
Riplock removed can make a drive noisier when playing back pressed DVDâ€™s on your PC.