Scatter brush animated stroke?

[Reindeer]

I know that the Scatter Brush can scatter animations. But can the actual stroke, or scatter, be animated?
Say I want a scatterbrush made of little animated dots that become larger and smaller. So, I create my little dot animation, cycle it and then tell Scatter Brush to use the clipboard as a source. Now I scatter, tracing an line from left to right on my stage. The dots follow this ideal line and do their little animated thing. So far, so good.

When I play it back or export the movie I see the line from left to right as a whole, with all the shapes I scattered appearing together at once.

But what if I wanted to see the actual stroke animate from left to right? I mean, what if I wanted to see the scattering progress like I see the stroke progress when I use the Animated Stroke script or the Stroke exposure tool?
As far as I can see this isn't possible. But just maybe...?

[synthsin75]

Since the scatter brush includes fills (where the stroke exposure and animated stroke only work for strokes) you'd have to use masking to animate exposure.

[Reindeer]

True, I could do that, good idea! Thanks.