I second the Tae Bo and the Bellydance ones. I also use the Leslie Sansone walking ones, the Firm Basics, and Pilates for Dummies. I have one that is just stretching, and they have standing, seated, and floor stretching, so you can do the one that fits you best.
My older tapes include A New You with Linda Evans. It's an absolute beginner tape, led by a positive, wonderfully easy to follow leader (I forget her name). It's in three parts, so you can do as much or little as you are up to. And they have people of all ages and sizes exercising, including one who is heavy, and doing a lot of arm and leg modifications to show you what you can do if you can't do the higher-level stuff. I learned a LOT from this video, even though it's not in my regular cycle of videos any more. But I took what I learned and am able to modify other videos now without feeling completely graceless and clueless.
I found I like dancy workouts, so most of my regular ones focus on that. Afro-Brazilian Cardio from the Method is fun, but the leader sucks. If you need precise, follow-able instructions, skip it. If you just want to move to some wonderful drumming, and like it a bit more free-flowing, go for it.
I also like Donna-Mite, which has a lot of 60s rock. She's definitely a dancer, but she's so easy to follow and does the routines step by step until all of a sudden you realize you're doing the whole combination, and the song is done. Time flies with this one.
I have the obligatory Richard Simmons tape. Sweating to the Oldies 3, I think. It's an intermediate tape, and sometimes I can't do the whole thing. But he's easy to follow and very encouraging, and he's got people of ALL sizes there with him. The music is wonderful. If you don't find him annoying and want to squish him, then I'd recommend at least one of his tapes.
Hmm. I have a bunch of them, but I can't think of more off the top of my head. I haven't been using them much in the last year.
The absolute BEST place to shop for exercise videos is
http://www.collagevideo.com They have people who actually DO the videos, and they tell you exactly what to expect. You can sort for type of exercise, level, equipment, everythign. The "Not Sure Where to Start" box in the upper left of their home page gets you into a nice search feature.
And you don't have to buy from them, of course. But if you're like me, and leary of spending your money on a video that you don't know you'll be able to do and aren't sure is your style, you may want to look up things here, get some ideas, and then take your list to Wal-mart or Borders or your local sporting goods store. A lot of video rental places also have a small selection of exercise videos. That's what I did when I wanted a Richard Simmons tape. I rented a couple of his to find out which one didn't make me want to squish him. *grins*
Good luck with your video choices. It can be a lot of fun.