On public TV here, there is a program called "Sit and Be Fit", it's targeted at senior citizens and the workout is done from a chair. I don't know if they offer videotapes, but it is a pretty decent program. I did it for a while when I was very pregnant with my son, the way he was carrying made it very difficult for me to stand, let alone exercise.
LOL they have a whole website! http://www.sitandbefit.org/