I made clear revisions to the paragraph, and posted it below. Its only minor, mind.

 As grunge came into being from a hardcore punk scene and was highly influenced by the genrea a whole, it is believed by some that grunge is a variant or subgenre of hardcore punk. In the video documentary Hype!, there is a scene in which a guitarist implies that grunge is essentially the same as hardcore punk. by plays two riffs on his guitar, claiming one as "punk" )in reference to hardcore punk)  and the other as grunge. This has caused debate about the similarity of the two riffs, , and the similarity of grunge and hardcore punk as a whole. Still, .... (insert Welsey and/or Leyasu's contribution here)

 In my eyes, it reads a little better (minor gramma fixes), and sounds a little less POV. Suggest this has a template for whatever else is added.