It is generally impossible to say what settings will produce the best output for a given situation, without simply trying various settings. Most encoders (I have never used Flash Media Live Encoder specifically) have quite a number of settings that can be tweaked within a specific bitrate, frame rate, and frame size that will affect the final result. Some settings will have better results for some types of video than others.
My best advice, without knowing anything about your specific software, is to try various settings and compare the results. You may wish to encode the same 10-30 second clib (probably with a lot of movement in it, since that's one of your main concerns) with various settings, and compare the results.
Another thing I might suggest is lowering your audio bitrate so you have a little bit more video bandwidth. Although whether that's a good idea may also depend a lot on what your audio stream is like. If it's a music video, then you probably want to guard your audio bandwidth very jealously. If it's an interview (unlikely since you're talking about a lot of movement, but who knows?) then you can probably get away with pretty low audio bandwidth.