Hi, I am trying to achieve an effect similar to what was done in Black Swan, where the actor is standing in front of a mirror and the reflection does something else. I have yet to shoot anything (I am just doing my homework) and I do not have access to a green screen.
If you haven't got something green to put on the mirror, then you can roto out your actor. The key is in shooting the reverse angle to replace the reflection and keeping it in the sync. You have to have one shot over the shoulder with your actor looking in the mirror then you have to have another shot looking at the replacement actor from the perspective of the mirror.. Sync the two up, do you masking/keying/roto, and you're done.