Some quotes from that piece:
"The kuffar, you can go to hell; this is not a Christian country. Christianity, you can go to hell."
"We are in East London, we are in South London, we are in North London... the police cannot stop us, the kuffar cannot stop us. We are coming to implement Islam immediately."
"... anyone who tries to stop us, we will take their alcohol, we will tell the women to cover up, and we will implement Islam upon your own necks... David Cameron."
Perhaps most scary is the soundtrack of gunfire behind the braggadocio commentary.
Yes these people are a minority and yes they are not yet much of a threat but how much more dangerous will they be if they link up with jihadis who have been to the training camps in Pakistan?