Well the first step after capturing the footage is to export it as a filmstrip, which you then edit in photoshop. Its basicly edited frame by frame, but the effect that makes it look like a lightsaber (lots of gaussian blurs etc) is done right at the end to the whole thing. This is the tutorial i did it from - http://www.alienryderflex.com/rotoscope/

Rotoscoping is editing on filmstrips in photoshop in order to create special effects.