you can keep the quality and have half the size in flv... sorenson works well... flash works decent for converting... depends on your movie quality...
as far as settings go... for flv
I use a custom setting... 1000 kbps 1 pass size settings... thats for high def widescreen vids I was processing...
by no means am I pro, but thats what Ive done and have been pleased....your best bet is to just process a couple and get it down according to your content and preference ...
