thi guy seems to have several songs of questionable origin.
the Castlevania "remix" is ripped right from the saturn Nocturne in the Moonlight
ex - actual gameplay a minute or so in.
and i'm pretty sure this is from DDR, from one of the universes i think, but i couldn't get any examples off hand, definitely a "Fifth of Beethoven" remix.
as for the carmina track, i saw several different sources on that around the nets, so i can't call it.
if someone comes across some viable examples for those two, then feel free to share, but i can't find a source that gives a proper name/artist for either.