Light Over Animation

First step is to make you sig and everything and make sure your text or whatever you want this effect to go on is a rasterized layer not just a text layer.

Click to enlarge

Use the settings shown

Now make a new layer(Ctrl + Shift + N) and make a small gradient like so

and then u should have this

Then when you have that hit Ctrl + g and switch the blending mode to lighten

Then move the layer ova the text so u can see the light ova the text like so

(i made mine red so u can see it)

Now switch to image ready there should be a little button at the bottom of the tool bar as shown below

Now duplicate the layer in the animation window

Select the first frame and drag the layer with you gradient to the left so u cant see it

Then select the second and drag the layer with the gradient to the right so u cant see it and reselect the 1st frame

Then click the tween button

and use these settings

(15-20 frames works good doesn't have to be 20)

Hit enter and bam your effect is complete.....