You may not find all of these on you tube. Warning, not for the weak of heart. Dream Theater can be pretty brutal if your not accustomed to Prog Metal, even though Repetance is a nice Pink Floyd kind of ballad.
The Glass Prison (from Six Degrees of Inner Turbulence) , Steps 1, 2 and 3
This Dying Soul (from Train of Thought) Steps 4 and 5
The Root of All Evil (from Octavarium) Steps 6 and 7
Repentance (from Systematic Chaos) Steps 8 and 9