typically, what is the file size of a 30-minute .avi video?

Answer 1

That can vary depending on several factors on how it was encoded to AVI. Generally, from what I've seen, a decent or good (and sometimes near-perfect) AVI 30-minute video can be anywhere from 200 MB to 500 MB, though on average between 200 MB to 350 MB. Again, this is just from what I've seen in my experience in working with video files.