Depends on the settings you used. 30 sec uncompressed can be 128mb. I recently did a 10 min movie for school, i rendered it to around 800mb for high quality. Another group did a 5 min movie that ended up looking like it was shot on a home dv cam, but due to their export settings it became 1.8gb. Try another codec, i use h.264 alot, its pretty good.