Learn music theory; specifically "functional" 4-part harmony to solve the issue of your music not being "in tune".
Learn the 7 basic triads that of the diatonic scales (Major and Minor) that are applicable in all twelve musical keys.
It might seem a little complicated at first, but it's actually really simple; you could probably get the hang of it in less than a week's time and you'll know how to effectively harmonize a melody and voice chords. All you need to know is seven chords, how to effectively change chords (voice leading) and just one scale. You should be well on your way in no time.
As for the samples, all you can do is become more experienced using them until you hit a brickwall (and you will) of what they're capable of and will have to purchase "higher-end" or otherwise "superior" samples that suit your needs.
I made this statement in jest. In all honesty, I requested recordings because I love piano renditions of VGM music. It's the only reason I wish I had learned piano in my youth.
I guess you could say I'm a bit jealous.
Generally not bad, though i didn`t like 8-bit part of it. My favourite part is after 3:35. Do you have piano sheets for it?
I can say it because it (along with the list of pieces i`ve played) was just an explanation why i`m looking for music of particular style and instruments and what difficulty i can handle on piano. I`ve never made video of me playing, but maybe i`ll try it on my next performance.