One approach is to use a mask to gradually reveal the line. Or similarly, use backgroundcolored graphics to cover the drawing and gradually move them away. Another approach, which may be along the lines of what was done in the sample you point to would be to gradually scale objects in some pattern... for that example you may want to see if you can contact the originators to get a better idea of what they did.
Here's a a little to plant a seed...
I got intrigued, now the rest of my day will be blown playing...
Just copy into the actions of a new as3 movie.
Dig more into the drawing api for more.
//setting the line starting position to the middle of the stage
var ox:int = stage.stageWidth/2;
var oy:int = stage.stageHeight/2;
// setting references for x/y translations
var tx:int = ox;
var ty:int = oy;
// setup a line to draw
var drawLine:Sprite = new Sprite();
//add a listener to fire at your framerate
//draw a goofy red line
//set high and low vals for the x/y change
var high = 5;
var low = -5;
// make random numbers between the high and low values
var goX = Math.floor(Math.random() * (1+high-low)) + low;
var goY = Math.floor(Math.random() * (1+high-low)) + low;
// add the new numbers to the old unmbers
tx = tx+goX;
ty = ty+goY;
//draw to the new coords -- I set the line width to the goX random number for fun
HTH, and have fun!
I've tried masks before, but they're not that helpful. And background graphics was actually the first thing I ever tried but I'm trying to resist it since it's not very professional plus I might be transferring symbols through several pieces of work so I need it all to be transparent.
I've tried masking before, but it never occured to me to use it like that..
I'll give it a try,