August Underground (2001)

After introducing his desensitised cameraman friend to a scene of numbing terror in his filthy basement, a sadistic serial killer starts torturing a helpless young woman tied to a chair, taking great pleasure in hurting her. And then, when the nightmare is over, the two brutal perverts embark on a killing spree on the streets of Pennsylvania and New Jersey. Now, the pitiless tormentors take pleasure in abusing, beating, dismembering, and killing the unfortunate ones who cross paths with them. Of course, the camera keeps rolling, capturing everything on tape.