Very good tutorial is it also possible to make two or three picture in picture transitions.
To show more then one short video samples at the same time.

Yes it is. Here is a video I made that shows 4 pictures on top of one.

http://www.youtube.com/watch?v=J28OrWyLdXQ

The trick is for each top clip to have a composite transition, use the same base track for all the composite transitions, and adjust the red rectangles in the composite transitions so they don't overlap.

Thanks problem solved