^^ True. It's ALL in the fingers/ writing. Whenever douchebags tune to drop Q and proceed to play syncopated diminished fifth palm muted drudgery I have to just shake my head. That shit doesn't make you heavy. Being a good player and writing heavy songs makes you heavy.
IMO the heaviest bands ever rarely ever tune below drop C. High on my list are Gojira, Neurosis, Lamb of God.
Anywho to the OP's question, no they aren't doing anything magical. That song you posted is def. tuned WAY low. They don't sound any heavier to me than all the other rise records formulaic pop/deathcore stuff. Actually my favorite part was the melodic chorus. The rest of it has been done a million times over.