great song, he uses his picking/right hand mostly but it looks like he's loosening his fretting hand so it mutes in that video. it doesn't really matter, i play it by muting with the outside of my palm on my strumming hand on the bridge. either way, a mute is a mute tbh.
Belief is a beautiful armour but makes for the heaviest sword.
im not sure where you mean but during the little solo bit around 2:05ish he uses his right hand. and around during the main riff he just lets off his fret fingers a little