That's not Islamist at all, it makes and it's not helpful to mix the two.

He says "allahu Akbar" but his remarks are about the death of people in Aleppo, where ISIS has / had a stronghold but where the majority of deaths and injuries have been civilians because the Syrian / Russian response is pretty much "we're going to kill anyone with ISIS, and if you're around or in the way you're going to die too"

It may come out in the future that he is a radical supporter of ISIS, but it's important to note that there are people who are not Islamist or with ISIS who have real grievance with the Regime.

Government forces are estimated to be responsible for the deaths of 150,000 civilians on the low end, and almost 500,000 on the high end Estimates of the percentage of Syrian Civilians ISIS has killed range from 5-15% of the total number of civilian casualties.

Most of the people fleeing Syria are fleeing Assad's and Russian forces more than ISIS.