Despite the security cameras, thieves seem to be targeting ATMs in record numbers, probably because the end result cold, hard cash is impossible to trace unlike stolen credit cards.
Person inserts a sliver of film into the slot, which traps your card when you insert it.
to make sure that nobody catches him tampering with the machine, he has a friend outside to alert him.

Once the trap is set, the victim enters the bank:
He inserts the debit card into ATM, and it gets stuck there!
The victim is surprised: "Weird, maybe this machine is broken?"
He looks around for advice,
Luckily there is someone eager to help to get the card out.
What "the helper" is actually after is the P.I.N. code:
"The Good Samaritan" convinces the victim to try to enter the code again
(he may blame the faulty keypad, new type of the machine,
or claim to know the "secret unblocking code", etc.)

As soon as the victim is gone, "the helper" returns to retrieve the card from the machine.
Now he's got both the card AND the P.I.N. code.
Check out this series of photos, which includes a device to copy your card and photograph you while you enter your PIN code, leaving you none the wiser.
Bottom line: If you see anything that looks out of place on an ATM you're using, don't insert your card, and inform your bank immediately.