The woman stands in the middle of the pavement while the man is smoking in a doorway.
Eoin Clarke, managing director of CCTV Camera Europe, which manages the block's security, said of the incident: "If you study the CCTV footage you can see two men on a moped looking for people on their mobile phones."
The bike, which carries a driver as well as the man taking the phones, first approaches the girl and zooms on to the the pavement to get close to her.
"He swoops around and grabs the girl's phone," said Clarke.
Immediately afterwards the suspects beeline for the man and snatch the phone right out of his hand as they pass and drive off into the road.
Clarke adds he is not sure whether this second robbery was planned or unplanned.
In both instances the victims undergo a moment of shock and then start to move towards the moped before realising that chasing is futile.
Metropolitan Police said of the crime: "Detectives from Islington's Operation Attrition are investigating the theft of two mobile phones.
"At approximately 17:20 a woman reported that while talking on her mobile phone, two men on a moped appeared and snatched the phone from her hand.
"A few moments later, and further up the street, a man also had his phone taken by two people on a moped. No arrests have been made. Inquiries are ongoing."
-Daily Mail