how to detect scene change (using RGBDifferenceFromPrevious?)

[KKLL]

I am trying to figure how to detect scene change. I have an AVI that is a screen capture from a Windows program. The screen remain almost totally the same except that a mouse pointer moves occasionally.
I'd like to create a text file where my scene changes (mouse starts moving). Something like this:

I noted that RGBDifferenceFromPrevious (an internal function) might work just fine except I don't know how to create the text file listing the scene changes.

I am new to Avisynth and if there's a better way let me know

[scharfis_brain]

try:

a=xxxsource("xxx.xxx")
subtract(a.trim(1,0),a)

[KKLL]

Thanks. Opening:
a=AVISource("myavi.avi")
subtract(a.trim(1,0),a)
..in VirtualDub shows a gray screen for every frame except show that have a change.
How do I generate a text file, containing something like:
Frame 100
Frame 250
Frame 255
..etc. which lists all the frames that contain a "scene change".