Why is ISIS recruiting deaf people?

This past weekend we shared with you the video produced by ISIS (or the Islamic State) in which two men sign to each other and tell viewers to join the ISIS jihad. Why are they doing this? In a piece published by the BBC the Limping Chicken's Charlie Swinbourne writes, "Few organisations and groups in the UK make signed and subtitled videos to communicate clearly with deaf people, so the fact that IS have made a fully accessible video could make them seem more deaf-friendly than many who are closer to home." Read his full commentary here.