What is the ruling on renting video tapes (movies) and video players to people for money?

It is permissible to rent a video player to someone known to use it for lawful purposes, and forbidden to rent it to someone known to use it for unlawful purposes. If the situation is unknown, the ruling is based on the predominant use: if the majority of people's use of the device is for good, then renting it is permissible; but if its predominant use is for evil, then it is forbidden.