I have posted a video-tutorial to show the way I use BorisFX together with Avid Media Composer to create a "reveal-route" effect.

The method can probably be used with any other NLE as well.
Just make the preliminary steps in your NLE and then when BorisFX opens follow the instructions in the tutorial.
In Pinnacle Liquid you will have to "slice" the part of the timeline that you want to apply the effect to.

http://www.gaijin-eyes.com/tutorials/mcborisfxreveal/mcreveala.htm

Regards,
Douglas

Douglas - not sure why your effect disappeared, but I suspect it is the render mode set in Boris - try switching renderers at the container level.. also set your preview mode in Boris to software only (not OGL where it uses your graphics card). Software only is the way it renders so you should at least know if your effect is going to work. You may already know some of things I've listed below but I hope they help..

Here's some tips for doing your effect.
1. Did you notice the default movement was set to easy ease? for somethng like the paint on effect I would use linear as it moves at a constant speed. using easy ease your animation will start slower speed up and then slow down on the end keyframe.

2. Clearly you need time for the viewer to take in the animation so you need to decide how long you want your animation to run and then how long you want it to hold before you fade it off. once you do this you can use hold keyframe after the animation has run it's course and teh animation will hold until it encounters a new keyframe. There are many uses for this - you could even pause your animation half way to demonstrate a base camp etc. To access keyframe interpolation, use the drop down box next to the sliders.

3. You can adjust the shape or do a more accurate path by editing your stroke using the node editor - it works in an identical way to the path effect in Photoshop, or nodes in Illustrator if you are familiar with that. In fatc I have edited the nodes on a tree graphic produce in Illustrator to give the impression of a tree growing - a slightly different application to yours.

4. finally if you run into problems with BorisFX, Boris RED or Avid FX (Boris RED in disguise) you can save the effect before exiting - this allows you to bring it up separately.

Thank you for all that information, John

It is extremely valuable.
I will be trying out your suggestions as soon as I have time.

If I get it to work I will change the tutorial to reflect the new knowledge!
Thanks again,
Douglas