What you do is get some text on track one then using a small centred circle in a title in track two move the circle over your text using keyframes. You'll need to be careful that it matches the text exactly and that it doesn't move to fast (you can always time stretch later). Also remember that you can scale your dot to avoid uncovering lines that are not being "drawn".
Next remove the text and export the movie of your dot. Now using the just exported movie put this on the timeline and use the "echo" effect. I did this in two stages to reduce rendering time - you can do it in one - but be prepared to wait! First stage use an "echo" with the following parameters (the numbers are for PAL - NTSC needs different numbers)
echo time : -one frame duration (-0.04)
number of echos : frames per second (25)
Starting intensity : 1
Decay : 1
Operator : Add
You should now have a "worm" that follows the text. Export this and then you're ready to create the effect.
Put your worm on track 2 and your text on track 1. Apply echo again to track two but this time have an echo time of -1 and a number of echos as the length of your title in seconds. Use track matte on track one with track 2 as the target. Apply a little time stretch and you're done. Time for a
Here's a demo: (again it's supposed to be 16:9 the gallery has it right http://muvipix.com/cpg/displayimage.php?pos=-2714 )
[wmvvideo]http://muvipix.com/cpg/albums/userpics/10215/Write.wmv[/wmvvideo]
The first part shows the effect and the second part shows the keyframes and the circle moving over the text.
It's actually not that hard to keyframe the movement as fonts lend themselves to bezier cures quite well.
Have fun!
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