According to the YouTube posting, the attack by a gang of 20 men took place at Yeshivas Ahavas Torah in Stamford Hill.
There were armed police CO19 units on scene, and a MPS helicopter above (but you won't see them in this video).
Let's go to the videotape.
A group of approximately 20 youths attacked a local synagogue in the London suburb of Stamford Hill over the weekend, yelling threats, beating worshipers and vandalizing property, according to IsraelHatzolah's official twitter account.I warned of this.
One witness belonging to the "Ahavat Torah" congregation described the mob as shouting "we will kill you" as they proceeded to physically assault the worshipers inside the synagogue and tear apart prayer books.
Another Jewish local who had passed by the scene rushed inside, grabbing one of the suspects with the intention of bringing him to the police, but was quickly overwhelmed by the other attackers and suffered strikes to the face, losing a tooth.
A spokesmen for local law enforcement said that the police views the assault on the heavily Jewish populated Stamford Hill community gravely and that they have already detained four suspects who say they were involved in the incident.
The assault on the north London synagogue comes days before the opening of a hotline dedicated to providing advice and support to victims of anti-Semitism.