Moving vertical bars in the background. How?

In many flash movies and especially flash intros there are some bars or shapes in the background which contineusly moves from right to left and left to right with fading and some gradient effects. Maybe the top logo in this page helps to see what I mean:
In this logo the vertical bars don’t fade in/out but I like to have this effect as well.

Do you have any idea how to create this?

mx-guest2004 :slight_smile: