Turbo Jam 20 minute workout. It's the video I always turn back to after a long hiatus from exercise. It's only 20 minutes, which to me makes it seem more doable than a 60 minute video. Plus the workout can be easily modified to a lower intensity.
Other things I've used are zumba / dance aerobic videos on youtube. There are lots of them.
And of course the ol' stand by ... Sweatin' to the Oldies.
Echoing the Leslie Sansone recommendations - I just started exercising with her videos a few weeks ago, and I'm actually excited about working out now (which is unheard of for this couch potato at heart!).