I do not understand very much about it. Probably my brother who is studying film in college would better respond to it. But in my opinion the FLV format with size 480x360 is very good. It is the same as youtube. The file gets very small in FLV format. Of course the size of the resolution and compression ratio will change the size of the file itself.
All in all, everybody likes of YouTube with FLV 480x360 size. Even youtube already have other formats, this is the most basic. Downloads fast and has a decent resolution.
Hope this helps