How do I use Handbrake and/or VirtualDub?

I have been trying to upload some things on youtube for over a month now. One is a short movie I play in, the other the video of our theatre, but also some TV interviews and so on. One of the problems I’m facing is that youtube doesn’t allow clips more than 10 minutes long, so I’ve had to cut them into shorter segments. But here’s my problem:

First I tried to cut the movie (10:27’) using Handbrake, but it won’t do it (or I couldn’t find it). VD does it, but the .mpeg that I had was the .vob file from the DVD which I had renamed. Since it was not a real .mpeg file, VD didn’t recognise it. I discovered a way around this (ok, maybe I’m stupid, but it seems to work): I rip the file directly off the DVD using HB, and turn it into an .avi. Then I open the .avi with VD, chop it up into segments, and save the segments as part1.avi, part2.avi etc. Then I open them with HB again and turn them into mpegs.

The system seems to work generally, except for a completely weird and new problem: the segments are far too large. I mean ENORMOUS. The original movie of our theatre for example (which is around 105min) was 1.2GB as an avi. The 11 segments were over 10GB each, more than 110GB in total (100 times bigger than the original movie). The same happened with the short movie I played in. After chopping off the extra 27 seconds, the file actually grew from around 600MB to 18GB!

So the first question is: why does this happen? I can understand why an .avi could be bigger than an .mpeg for example, but how can half an .avi be much bigger than the original .avi it came from? (framerates and quality etc are all the same).

Secondly, since youtube does not allow files larger than 10min or 2GB, how can I chop up the movies into uploadable pieces (probably have to turn them to .mpeg, right?) using either Handbrake or VirtualDub, or both?