In addition to the centroid, It would be nice to add "area of motion" to motion(). This would be calculated as the normalized size of the rectangle (findbounds) of the motion "blob". I think this is implemented in the Max version, or at least in the original Max version. For a video with only one person, this number says something about the kinesphere of the person.
@joachimpoutaraud has added an area of motion (AoM) parameter to the motion data function of the Toolbox. You can find more information on the wiki tutorial of the MGT-python.
In addition to the centroid, It would be nice to add "area of motion" to motion(). This would be calculated as the normalized size of the rectangle (findbounds) of the motion "blob". I think this is implemented in the Max version, or at least in the original Max version. For a video with only one person, this number says something about the kinesphere of the person.