The video footage shows a man apparently pushing a woman, who then appears to lunge mouth first at his arm. Both then continue to push and jostle one another until they get off at Kings Cross and complain to staff, the mad showing his ouchy arm.
Although this happened last year not incident was reported and police are now trying to track down the pair.
Anyone with information is asked to call police on 0800 40 50 40 or text 61016, quoting the reference 274 of 25/06/2014.
Balloon animals have appeared in many carriages on the London underground and no one is quite sure of the identity of the man who put them there.
The balloon animals, like those made by children's entertainers were added to certain tube carriages yesterday on the northern line.
Julia Boggio tweeted: "Man just came onto the tube, put up loads of balloon dogs and then sat down to read a book."
The balloons lasted on the tubes until they were removed by cleaning staff.