I think about a strand of 500 to 700 pixels that i'd like to program with images instead of programming the effects by properly coding. For about 5 or more fps I quickly run out of FLASH if the animation is supposed to be longer than a couple of minutes. However, plan B is to attach an SD-card and space wont be an issue anymore. So, indeed it was more out of curiosity if you thought about it so far. RLE within a bitmap might indeed work well, since I expect many effects to have a couple of blacked pixels in a run, which should compress well then.