Lou,
There is no functionality out of the box for creating/reading AVI files.
You will have to use functions through the P/Invoke layer, or through COM
interop, or use a third party component.
You might want to look into using DirectX 9, as it might have the
libraries you want to manipulate AVI files. Also, if Movie Maker is
installed on your machine, I would assume there is some sort of API
associated with that as well which you could access through COM interop.
Hope this helps.