The fight between Seras Victoria and Zorin Blitz from the seventh episode of Hellsing Ultimate. The end is possibly the most epic moment in the entire series and also made Seras into my favourite character in place of Alucard or Andersson. Or, at the very least, on par with Alucard and Andersson.
The song starting at a little past 8:00 is Zakuro by Suilen.
Also, if you wonder why the subtitles stay until replaced by new ones, that happened when converting the Matroska video file to something Pinnacle can recognize.
MAG.MOE - The MAG, The MOE.