When rendering FLV for the web, there are two main considerations:

1. Progressive or streaming?

2. Flash version compatability.

Additionally, with screen capture videos, you may need to consider how you approach keyframing.

Streaming requires a streaming server. If you don't intend to use a streaming server service (most pro's do) then you'll have to use progressive. It's ok. It'll still work.

Flash version compatibility issues will influence which codec you use. Essentially, flash 8 can use the excellent on2 codec, but can only be viewed with flash 8. Personally I'd go with this, but it depends on your target audience.

Keyframing is important with screen caps because you need to ensure that significant changes on the screen such as menus popping open and windows opening are keyframed immediately, otherwise it looks odd and rather cheap.

Some flv encoders use 'intelligent' keyframing that produces a new keyframe when significant changes occur.

Having made these important decisions, you are then able to experiment with compression settings and data rates etc.

I've never worked with screen caps, so I can't really say.

Finally, you will need to encode your flv. Adobe Flash can do this, but it offers little control especially with keyframing. Sorenson squeeze is the favourite, but it's expensive and I hate the way it does what It wants. On2 have an encoder called Flix (I think) which is supposed to be quite good. There are countless cheaper flash video encoders about. Can't really recommend any in particular.

Rgds