http://forum.videofitness.com/index.php is a forum devoted to those of us who exercise at home to videos/DVD's. You will find opinions, reviews, rotations, help, and encouragement.
http://www.collagevideo.com/ is a retail site. Collage has clips, reviews, breakdowns, and a small forum. You can also chat with CS who can answer questions and point you in the right direction. Do a search for 'beginner' workouts, and see what you can find.
http://www.totalfitnessdvds.com/ is another retail site, also with clips, reviews, and information.
Netflix or Blockbusters online site also have workout videos. Comcast has On Demand workouts. Direct TV has FitTV and there is Exercise TV, the pay-per-view of workouts {never tried them however, so I don't know how the workouts are rated, beginner, intermediate or advanced}
Your local library would also be an excellent place to start. I've started working out at home in '06 with a WW VHS from the library, that was about 20min long but since I had never exercised before I treated it like it was a marathon, LOL. I"ve been consistant every since. Some of the members of VF forum have been exercising at home for the past 25 or so years; they started with Jane Fonda's record album and are still going strong.
Hope you find what you are looking for.