I'm trying to recreate a raindrop effect, such as this one: http://flash-effects.com/tutorial-create-a-water-ripple-mouse-follow/
Any ideas how to find this tutorial online or how to go about doing it? Does it really require purchasing/downloading a separate filter?
For the example you point to, yes, it will likely require you to purchase the component to use it outside of a trial scope.
If you search Google using terms like "AS2 ripple tutorial" you might be able to find a tutorial that you can use, though it may not be as dynamic/animated as the one that's for sale.
Here is an excellent AS3 example:
Perhaps you could use that to figure out how to take it back to AS2? Or move yours to AS3?
Also I think I might have something at home. So I will check tonight.