In the following image you can see a Spanish camera used to record the PINs that are entered in the ATM, works with motion detection to save energy:
(click to see larger)
Although the color draws attention, given its location and design, it could confused with a security cameraIn fact something like that happened. It was detected by maintenance personnel one day after the dummy slot was removed by bank employees.
On the Brian Krebs blog you can find more information about the case and photos.
The cameras work in conjunction with other devices that are placed in the slots to copy the information of the magnetic bands. With this information, criminals can clone the cards and then withdraw their victims' money at any ATM.
A good security measure that we can adopt is cover the keyboard while entering the PIN, as you can see in this video, this way if there is a hidden camera the PIN will surely not be recorded. We must also check that there are no strange things in the card slot and even on the keyboard, in some cases fake keyboards are used instead of a camera: