Record using the FRAPS file size enormous?

I record a game of modern warfare call of duty 2, using FRAPS with a format applications.
Avi length is only 24 seconds, but why the size is too big that is 400 MB. I want to upload it to YouTube, but if the size of it with my internet connection is slow, it may be a full day.
Whereas films with a length of 30 minutes with 3gp format just are not up to 30 MB big, how do I shrink or compress to her?
