Photoshop was used to remove actors from pre-existing footage from television shows. The footage was then tracked and new actors were inserted. Great for anyone wanting to guest star in a show that was cancelled before its time.

Both Law & Order and Star Trek: The Next Generation presented interesting challenges.

Star Trek: TNG had fairly stable cameras, and so motion tracking was minimal, however its lighting and the standard definition footage was challenging since the light sources in the original footage were complex and lit both actors individually as well as the practical lighting generated around the table.

Law & Order was also shot in standard definition, but unlike Star Trek its lighting is fairly direct since the courtroom is a large open envrionment. However, the camera movement was a tough track since it's only noticeable on fairly close examination. Because of the careful steadicam work, the movement is subtle enough that tracking must be very precise in some shots, or the normally minute movements will be very clear to the viewer.

Law & Order scenes were particularly succesful and actually required a reshoot with the actor deliberately eating popcorn since his presence wasn't noticed by initial audiences in the wide shots.