Software to Remove a Person from a Video
You could export the video to still frames, then the problem is reduced to removing the person from pictures.

You can use Gimp or any decent paint program with a clone tool to copy sections of a good image to the image that needs correcting.  The clone tool is pretty quick to use.  But yes, at 30 fps if your perpetrator is in the scene for 5s is a lot of frames to tinker with.