Lachlan Barclay (of ToeHider) composed music for these videos:
AVGN: Chronologically Confused About Zelda (Theme cover)
AVGN: Mario 3 (Battle music)
BOARD JAMES: Crossfire (Crossfire theme)
The Dragon in My Dreams (Opening and park scene)
AVGN: R.O.B. (Most scenes)
Now he is making his music available for download on itunes.
They are also available on Bandcamp.com which includes bonus tracks. (this one includes Crossfire and video game cover tunes.)