Cake goes to the people who know the song that this is from. 
Since there wasn't a thread about metal yet, I figured I should start one.
Basically, what styles metal y'all are into, and what bands etc. What really sets you into a headbanging mood?
I'll start the ball rolling with my all-time favourite band: Killswitch Engage. Videos are contained within spoiler tags.
Killswitch Engage videos
They underwent a vocalist change after two albums, and they went from this:
...to this:
Their current album has this song from it, and I'm currently covering the vocals for my band:
The video's absolutely hilarious; only Killswitch could get a "Your mum" joke into their music video...

Another band I listen to copiously are SikTh, who, unfortunately, broke up about 4 years ago:
SikTh videos
One thing to know about them is that they arewere very progressive metal-ey, and they had two vocalists. Go figure... Anyways, undeniably their best song:
Another of my favourites is this:
I'll finish with a band I hadn't heard of until recently, called Periphery.
Periphery belong to an unusual genre called Djent. Essentially, it is progressive metal combined with groove metal, which makes for a very enjoyable combination.
I particularly like their vocalist, who has an incredibly diverse vocal range, which is one of the defining characteristics of a good metal band, in my opinion.
Periphery videos
This song is just so catchy:
And this song, which has been re-edited for the video, but, in my opinion is better, as it demonstrates Sotello's (the vocalist) amazing vocal talents:
I'll update with more examples of good metal after going through my iTunes library. 
I'll leave you with a discussion point: what makes a good metal band? Or, indeed, what makes a good metal song? Discuss.