Way to remove image/words from a sign

I have a video of a show on stage but there is a sign in the back round that has pictures and words on it that I would like to black out. But in a way that makes it look like it is not there... not in a way where it looks like I just put a black rectangle over it especially since performers walk in front of the sign at times. Is there a plug-in that will mask something like this and still let people walk in front of the masked object?