Benjamin,
Cool example video. I love how they mix stuff up. Anyways…I use Snapz Pro and have created lots of tutorials with it. Here is an example: Creating a Hologram
All of the move where done in Motion with the Camera. If you want to do the Weight Watchers thing you will probably want to move the clips themselves or put the clips in groups and move the groups. You are going to have a lot of fun creating this project. By, the way, if you have not purchased Snapz Pro it has a 15 day free trial.
You may want to take a look at iShowU as well. There are even more screen grab software options if you want me to list them. Best of luck and have fun.
Utah Video Productions
Check out my Motion Training DVD
Check out my Motion Tutorials