umm good effort
but you needed to bend the pitch, it was way too obvious where they were joined, this shouldnt happen, if you wanna make a good extended mix then it is fairly simple just by cutting and looping portions of the original track, that way there is no pitch/key difference.
I'm trying to be helpful and not negative so take a bit of advice from someone that knows, dump the karaoke stuff, it just makes it sound thrown together which i know it obviously isnt. Practice pitch bending and looping instead, the results are far superior, dont know how to post music tracks so cant show you what i mean
just me being daft but i wish you hadnt touched this one, pay no attention to that