I can see how someone could mistake this for Dutch (and more particularly, a specific Flemish accent), but it's not.

The stuff they're mumbling before the shot doesn't sound Dutch at all.
The first thing he keeps on repeating right after he shoots ("Allah guh akmar" or something) doesn't sound Dutch at all, the second thing (sounds indeed like "Adhum el garath") kinda sounds like a Flemish dialect version of "Heb je hem geraakt?" ("Did you hit him?"), but is not (the "k" sound is missing, among other things - not Dutch at all).

And the guy clearly says "la", not "ja" ("ja" is Dutch for "yes").