tmpg VBV buffer? what does that do?

[Trifu]

Hi, I'm encoding a video to mpeg-1 at 2000Kbits/sec
the original avi file isn't blocky at all, but when I convert it to mpg, during the fast pace scenes it gets quite blocky, I'm wondering if I set the VBV buffer to a higher setting, say like 100, would that help the quality of my mpg video at all?