Hey Choco and welcome on NU. ^^
Nice you try to do Nightcore. So you asked about our opinion of you channel? Here we go: :D
I personally don't like what you uploaded, but is more beacuse of a view we have here. What you uploaded we woud never call Nightcore, for us these tracks would be only Speed Edits or Fakecore. (If you want to know more about this feel free to ask or dig through the threads)
Anyways the way you did tham is most times good except for "Alan Walker - Alone". This track is much overpitched and sounds only squeaky. I could listen to a Chipmunk Version and wouldn't even notice a difference except the speed.
Anyways the videos ar okay, they are not overloaded but it is always good to experiment with the Layout and the design. ^^
And the sound quality is pretty good, i can't say anything negative about it. ^^
EDIT: A little bit less pitch would be much more. But this could be only my personal taste about it.