Step 1

Create a new flash document, press Ctrl+J key (Document Properties), and set Frame rate to 40fps (Frames per Second).

Step 2

Take
the Pencil Tool (Y) and under Pencil Tool Options, set Ink. After that
open The Properties Panel (Ctrl+F3), under Stroke Height set 1px and
under Stroke Style choose Solid. Look at the picture below!





Step 3

Open the Color Mixer Panel (Shift+F9), for Stroke Color choose white and set alpha to 18%. See the picture below.



Step 4

After that, draw a lot lines (different size), like it is shown on the picture below.



Step 5

Then click on some lines and set its Stroke Color to white.



Step 6

Click
on frame 2, and delete the lines that you just have created. After that
create a new lines, different sizes and locations. See the picture
below.



Repeat this steps about 20 times. If you like, you can insert some old picture in flash, and set its as background.

We're done!