I drove my car home Saturday night and noticed an odd noise while backing in the garage. It was late and I didn't think much about it. Then I went to drive it this morning and the noise was very distinct. I hear a slight belt squeal which I'm not worried about but the knocking noise is the concern. If I rev the motor I don't hear it until the rpms slow down again. Check out the following video taken from under the car passenger side:
What is this noise uploaded 6-18-2012 - YouTube