I know there are specific videos out there for the bigger gal. Ya know, maybe a larger person who can't do a regular video, maybe has trouble walking distances, too heavy for the Wii Fit....etc
Have you tried the Leslie Sansone Walking Away the Pounds DVDs? They are pretty easy going and you can always do any DVD at your own pace and work up to the harder stuff. She have DVDs where you can do 10 min. or a mile. I think the important thing is to start out with a few minutes a day and work your way up.
I second Leslie Sansone. Try to find her older ones, with the Walk away the Pounds Series. They are the best for those just starting out. No jumping around. If you can march, kick (forward & back) and lift your knees you are set.