In brief...
The customer is well known to staff. She regularly shops in that branch of Aldi and is abusive to staff.
In this instance she was being served by a member of staff she has previously abused.
The shopping was run through the till and the customer gave over the (I believe electronic) codes from her Child vouchers.
This basically means £20 was deducted from the total on the till.
Instead of just paying the remaining bill the customer then decided to start doing some Internet banking on her phone, causing other people in the queue to start telling her to hurry up.
The customer then starts an argument with them and the checkout operator asks her to pay the balance and leave.
Customer then starts to shout and cause a scene, which she has previously done in store.
Because the customer is threatening, abusive and swearing the checkout operator (according to store policy) shuts down the till and tells customer to leave.
Customer starts demanding £20 in cash from the till in compensation.
The rest is when the video starts.
All of the other customers, staff and the police are backing up the staff member. This is grifting at a whole new level. She's just vile.
In the hope of being able to leave without paying the extra - or to get cash instead of a supermarket voucher, by any chance?
Vouchers cannot be used for age-restricted items, such as alcohol, cigarettes or lottery tickets., after all.