I want to accomplish an animated text effect where a translucent box containing the text of my commentaries fades as it is bumped up a certain distance (less than half of the video). To clarify what I mean by this:

1) I make an audio commentary, a colored, translucent text bubble appears.
2) I make another, and a second text bubble rises from the bottom margin of the video, bumps the first bubble up.
3) First bubble becomes (more) translucent.
4) Eventually, the text bubble is pushed out again, and at that point, it has faded away completely.

My current strategy is just to use GIMP PNGs and apply a fade-out filter for it, but the actual moving part might be more tricky. I'd like it a lot more if I could somehow automate this effect or something, but I'll take any real strategy that accomplishes this text effect for me.

affinecomposite can move pictures/text using keyframes. is that what you mean?

Affinecomposite is a transition. Okay. I created a title clip for the subtitles, but the composite containing the affinecomposite transition doesn't seem to affect the clip at all. I am able to create keyframes and play with the shearing, but nothing seems to work.

I don't think shearing is exactly the effect I want to go for, but if I can work around it to make it appear to be moving, somehow, I think that could work for me.

ok, you put your video footage on the second row (referred to as video 1), you put your pictures of your sub-titles you said you were going to create in gimp as png files in the first row (referred to as video 0). you apply an affinecomposite transition to the photos of sub-titles, you mess with the y option at different numbers and also changing the keyframes so it appears to be sliding up as you wanted. make sense? i am sure there is a youtube video out there showing this.

Oh yeah, I read you loud and clear, there. If that's how to do it, then maybe I could go on to do something more advanced, too. :)