bml is a markup language for animating balls. bml files look like:

giant_red_ball:
  color: FF0000
  radius: 100
  appear:
    time: 19
    x: 57
    y: 52
  disappear:
    time: 29
    x: 107
    y: 52
tiny_yellow_ball:
  etc. etc.

Write a swf that lets you load bml files from an arbitrary URL, and then plays them back.