It does play nicely full screen,
but claiming a dialup user can stream it is a bit much
Mutt
Divx can be smaller than mpegs.
They are easier and quicker to code, maybe that's why you see them alot, you can do it in premire same as an AVI, but for an mpeg you need to use another prog.
I like WMV files aswell, you can get great quality at a low rate but not everyone can see them.