MPEG-4 into vid editing software looks like shit, how can i fix?

[davidkim]

so, im trying to get a movie that i wanna watch,

i just downloaded all 12 parts of the movie. Sadly they are all mpeg-4 clips. i usually open them in quicktime by the way, and quality is pretty good when i watch it.

anyways, i just happened to have sony vegas, so i just dragged all 12 parts.
so, it looks good and all. However, when i play it [the whole 12 parts together after i publish it with sony vegas], it looks like shit..
in random scenes, green square(s) appear all over the screen. How can i fix it so the quality is as good as it can be, or atleast as good as the quality it played at when i opened the video with quicktime?

[zoobie]

increase the bitrate