Ha, if I'm honest, the reason I like Zarx is that I just set it to 'highest quality' and 'film' and it thinks about all the rest for me. I'll have a look when I get home and see if I can figure out what that actually means in terms of settings.

(And now I'm wondering if I was just really shitty at compressing avis all this time, and that's why I've seen such a huge difference! :))