If you're looking for videos specifically for bigger people, here's a site I find helpful:
www.plussizeyellowpages.com/fitness.html
Browse the links, bigyogaonline.com looks interesting to me.
From the yellow pages site and amazon.com searches, I've made a list of videos I want (but haven't tried, so can't endorse) I used to love the Richard Simmons videos, but his voice got a little annoying to me over time. I wish there were an option to hear only the music (and maybe have the instructions in closed captions).
Anyway, here are a few of the videos on my list. Some might no longer be available from the publishers, but I buy used from amazon a lot (which are often actually unused bookstore stock).
Great Shape: The First Fitness Guide for Large Women (Paperback)
(this is a book, but I've read it, and it's really good)
Real Fitness for Real Women: A Unique Workout Program for the Plus-Size Woman (Paperback) Also a book, haven't read this one yet, though.
Yoga: Just My Size With Megan Garcia (2005)
Yoga for the Rest of Us with Peggy Cappy
More Yoga for the Rest of Us with Peggy Cappy
Yoga For Inflexible People
YogaFit Plus: Yoga For Real People
Yoga for Round Bodies, vol. 1 (and 2)
Fitball 101: Exercises for Plus Size and Under Active Adults
(I REALLY want a fitball)
Total Stretch for Beginners with Tamilee (2001)
The Art of Exotic Dancing for Everyday Women 3 DVD Set! Core Moves, Develop Your Routine, and Chair Dancing (2001)
Sit and Be Fit: Fibromyalgia Workout (because I have fibro, there are also a bunch of other Sit and Be Fit videos)
Jodi Stolove's Chair Dancing Around the World (she also has a bunch of other Chair Dancing videos)