In the 13-minute video, entitled “There is No Life Without Jihad”, the group – including three claimed Britons – explain their motivation for travelling to Iraq and Syria and seek to persuade British extremists to give up “the fat job … the big car”.
One of the British men in the film, which calls for their countrymen to answer the call and "fight for God," is a 20-year-old aspiring medical student from Cardiff.
Nasser Muthana, who goes by the name Abu Muthanna al-Yemeni, travelled to Syria with his 17-year-old brother Aseel Muthana after disappearing in November.
His father, Ahmed Muthana, told the Daily Telegraph that his elder son had been accepted at four universities to study medicine but did not go.
Instead he thinks Muthana, who went to Cathays High School, enjoyed swimming and football, became “brainwashed” and radicalized in the UK.
The British government says it is treating the growing threat from ISIL with ever-greater seriousness.
On Thursday, the terror group was added to a list of banned organizations, making it an offence to be a member. Four other Syria-linked terror groups were banned at the same time.
Prime Minister David Cameron has insisted “everything that can be done is being done” to stop Britons being radicalized overseas amid fears that 450 people have joined the ranks of the extremist group in Iraq.
Experts believe the method of appeal in the video mimics that of Western charities and aid groups.
Joseph Carter, from the International Centre for the Study of Radicalization at King's College London, told The Times: “There's no question that the purpose is to attract Western audiences and to convince them to come.”
NTJ/HH