Sober said:
Superman II - Removing 'Duane' the Policeman as Zod and co exit a cafe (just before the English kids dad is lofted up in the air

I plan on showing how that was accomplished in an extra on the DVD release. But basically I created a clean (meaning no foreground elements) static background plate in photoshop using several frames from the video and hand painting. Then I created an animated matte around Duane in Aftereffects, and used the background plate (motion tracked to match camera movements) to fill in the holes. When Duane moved in front of someone, I recreated that person using a combination of cloning from previous and future frames, and hand panting. The trick to making it appear seemless is to hide the edges of the matte in areas that are high contrast (preferrably along straight edges that aren't moving) and re-watching it an insane amount of times, and painting out each problem over and over again until it looks right. If you want good results, it's tedious. But the tools nowadays let you control every single pixel in every frame, so theoretically nothing's impossible.