From chuck_boyce_jr:

For a high quality FLV, you can use these settings: 872 kpbs; max bitrate framerate: 24; two pass.  However, if you are inputting your FLV to a transcoding process be aware of the defualts employed (i.e. blip's flash transcoding process defaults to 15fps. This would make your 24P stuff unwatchable if you inputted it to their transcoding process. For 15 or 30fps sources, you'll get a very good result with blip.)