According to the help file...

Magnetic objects

You can attach a video, picture, or text object to moving picture content of another video. The " object" automatically completes the movement of a picture element from the film. For example, you could use this method to insert a hat that stays on someone's head throughout, even if the person hops through the picture.

Let's roll:

• Place an image object (e.g. a photo of a hat) on a track below a video with a corresponding image element (e.g. a walking person). The picture element should have enough contrast in it (bright-dark difference) and should have a consistent size.

• In the Media Pool under "Effects -> Movement effects -> Position/Position", you can match the zoom of the image object to the video and then position it precisely (i.e. add the hat to the person).

• Right click on the image object and select the "Attach to image position in the video".

• In the "Attach to image position in the video" , click on "Change size and position".

• Select an image section in the preview monitor using the mouse which you would like the image object to follow. This section should have as high a level of contrast as possible.

• Calculation of the object movement starts automatically.

Now, I tested it out and yes, it starts the process, but you might need to work with it a bit if there is a great deal of movement. I had to cut edit my video in places where the movement was to fast to make smaller sections so I could mosaic the face of a dog running. Regardless, it works as they state in the help file.