Hard Vocals

Why do you need to do that in the first place? I'm pretty sure that's just a show for the video.
 
Screaming/singing through your teeth (not really opening your jaws) sometimes sounds pissed off. But that might not be what you're searching for. But give it a shot. An make sure he's drooling like a dog also.
 
I don't really have this problem, my vocalist is pissed off all the time. Only thing is we're a prog metal band with pretty piano parts :lol:

I've found using a mic he's familiar with (SM58 or similar) always helps to get a better (read: more pissed off) performance out of him, though. Usually he just goes nuts and belts it out as if he's onstage.
 
Make sure the vocalist is articulating clearly.
Make him/her put special emphasis on consonants.
Never ever let the singer walk away from the mic or stop a word before the line is sung completely. (for instance, a line that ends in the word Demons. Make sure the last s really is there and clearly articulated). The explosive consonants and singer sounding "in your face" all the time is what makes the track sound pissed.
The vocalist really needs to feel the song and be accurately on time.
Try recording in the control room with the monitors blasting.
The absolute key is to loosen up the singer so that the whole recording situation feels like he/she can do anything without being laughed at and without thinking "what are people going to say about my vocals on that part". Ones voice is deeply personal and revealing thing. Singers get embarrassed easily.

Make sure he/she is over articulating, and "over the top" with the performance. It's much easier to get the singer to back off a little than it is to get him/her to loosen up.

And remember that the compression that is likely added later on will pull down the articulation and the consonants.

Make the vocal recordings easy going and positive. No one will sing good if you throw them with stuff or call them names.