Grainy footage shows bottles and flares being thrown during an alleged Neo-Nazi attack in a Tottenham park.
The video, posted to YouTube on Saturday, shows fighting between two groups of men, including some thought to be members of an extreme Polish nationalist group, Zjednoczeni Emigranci.
Police ask one man to move away as he stands with his arms outstretched, before another takes off his T-shirt and begins hitting bystanders with it.
The incident, which took place at a community event in Markfield Park, led to one person being stabbed.
The victim was taken to hospital, but later released following treatment for superficial wounds.
Nobody has been arrested in connection with the stabbing.
A man has been charged with religious and racially aggravated common assault for pushing a Jewish man's kippah from his head.
He has been bailed to appear in court.