I have a video that was shot with a person sitting in a chair in front of a pop-up banner. I would like to remove the banner specifically. I would be happy to insert some generic background if possible or try to copy the non-banner background and super impose it over the banner. I believe this sort of stuff can be done in Photoshop for images but not sure how, if at all to do this in a video?
Any guidance would be appreciated.
It's called rotoscoping. There's the magic word for you! now all you need to do is fire up an Internet search on how to do it with masks and other tools in AE.
Here's a good place to start to learn about compositing in After Effects:
Start here to learn After Effects: