In the Star Wars movies they use rotoscoping to create the effect of the lightsabers, as well as other effects but the most prevalent is the beam of the lightsaber. In this process the beam has been created an animated frame by frame to look like it is coming from the handle prop that the actors are holding.
This isn't especially relevant to my project but it is a good example of adding rotoscoped elements to live video.
http://www.youtube.com/watch?v=MFEjcvIRMDo
