Ok, I've heard about green screening, where you set up the green screen, shoot your video, then replace the green with an alternative background or video. I'm not talking about that. What I want to do is cut out one person from an existing video and place them into another existing video where no green screen was used in either one. I've seen this done with stills, where you paint the section you want masked off green on one still, but what about for video?
Can you use Vegas to do this or how is it done? Here is a funny example where Obama is cut from an Ellen show and placed into Mortal Kombat
YouTube - Barack Obama Terrorist Fist Jab Fatality