This video has replaced a previous one for legal reasons
The man who filmed the graphic video of a knife-wielding man in Woolwich has explained that he was assured he was in no danger.
The man, who wished to remain anonymous, said the bloodied man came straight for him when he saw he was filming and told him he was not under threat.
He said he was told: "No, no, no - it's cool, I just want to talk to you."
He was initially a little scared but soon realised he would be ok, he explained.
He said the man could have escaped but wanted to explain why he had carried out his actions.