In the video a man wearing a bucket hat can be seen waving an axe above his head in the kitchen of Palash Balti.
The teenage victim, who works in the takeaway, is pushed in the chest by a man wearing a baseball cap and checked jacket before being threatened by the axeman.
WATCH the video here:
West Midlands Police said the footage was filmed shortly after the same teenager was attacked in a "road rage incident" outside the takeaway, which is part of a parade of shops just off Birmingham New Road in Parkfield.
The men held an axe to the 19-year-old's throat and punched him repeatedly before escaping in a black Renault Clio.
The man who pushes the victim in the video was also responsible for attacking him outside the restaurant, police said.
The attack happened at about 6pm on September 4 but the video, filmed from the customer side of the takeaway counter, was only released by police today.
Officers are keen to hear from anyone who witnessed the incident or who recognise the men shown in the video.
Anyone with information is asked to contact police at west-midlands.police.uk or by calling 101 quoting incident number 20WV/210555C/19.
To stay anonymous call Crimestoppers on 0800 555 111.