Following ghost type thing?

Hi,

Can anyone help…?

I’m try to do a ghosting type thing where a box moves across the screen then back again.(This effect I’ve see so many times it must be a flash classic but I have no idea how it’s done?).
The thing is I’m after a sort of ghosting following it as it moves which is affected by its speed ie the faster it goes the ghosting becomes stretched then as it slows down the ghosting catches it up.

Anyone have any ideas?

Thanks

Spence :-/