Eh, I don't feel like finding the videos (Some of them are likely somewhere on this list already) but here they are:
Kingdom Hearts Birth by Sleep - Vanitas Battle
Final Fantasy VII Crisis Core - Why (CCFFVII Mix) (On a side note, I always cry a little inside when I hear this)
Phoenix Wright Ace Attorney - Trial
Kirby Nightmare in Dreamland - Rainbow Resort
Sigma Harmonics - Bright Invitation ''Dance of the Iron Ox''
SMT: Persona 3 - Soul Phase (Long version)
...More I don't want to list