OK can anyone tell me who did this...

[Doctor Who?]

At one point on the Track Mike or Al do a Comic Book Guy that is so dead on i can't tell who is doing it,does anyone know because it was perfect.

Oh and Al is now also my favorite Riffer.

MORE AL!!!

[Cosmic Muse]

I'm going to take a stab at guessing and say it's Weird Al.

[Asbestos Bill]

Sounded like Mike to me. It was the same voice he used for "Worst harvest ever" from one of the Star Warses