Newbie question: How does MM know where to split clips?

[Opinicus]

I just used MM for the first time to capture a Hans Conreid quip from an old
Maverick episode recorded in an .AVI format. Amazingly, MM caught the
beginning and end of the quote perfectly. (It began and ended with a
full-face shot of Conreid.)

According to the MM help file:

<quote>
If you import a video file that is not a Windows Media file, such as a video
file with a .mpeg file name extension, a clip is created when there is a
substantial change in one frame of the video compared to the next frame.
</quote>

How does the program "know" how to do this?

 

[Graham Hughes]

It looks at the frames and if ones got a head on it and the other has a
river it knows they are different so makes a cut.