>Safawis

Are you sure they did not say Safavids? If so they refererred to the Safavid Empire; a shia Persian entity that existed between the 16th and 18th centuries.

In context the term "safawi" is used to denote all those that are shia... and with ISIS being a sunni terrorist organization, its rather obvious/expected for them to hate all other sect of Islam/religions

Can you link to the videos? Are you sure you mean Salafis/Salafists and not Sufis? Generally, Salafis have been Islamic State's primary ideological backers and when you hear about preachers and groups outside of the Islamic State backing IS, they are often associated Salafis or closely associated with Salafism or one of the similar "originalist" movements. Sufi shrines, on the other hand, have been one of the primary targets of IS attacks.