For one of the graduation projects I produced at the London Film School we had a problem where the shot the director wanted to use had a bystander walking into shot. Below is the result of removing the bystander using Nuke. The process was relatively quick as they did not cross between the actor and the camera. I tracked and stabilised the shot, created a clean plate without the bystander or actor, and used a very rough matte to remove the man walking across the shot. More difficult was the shadow of the bystander which passes behind the actor, so I needed to do some fine roto to remove this. Finally I reintroduced the original camera motion to the shot. Below is a video showing before/after the bystander was removed from the shot.
