Those low notes and growls have some serious power behind them. It sounds awesome~ I hope he isn't hurting his throat to get them out, though. Really cool video, as always! I love how energetic he is; it really adds to the song~
the thing you call 'growls' i call them 'rasps' and i do this often. it doesnt hurt to push out at all if you dont have a sore or dry throat. there's no need to worry ^ ^