DVD/Video covers may give you clues about the length of the workout, target fitness level, required equipment, and workout structure, but they aren't always accurate or specific enough. For example, many videos say "for all fitness levels" on the box, yet most do have a specific target audience. You should be suspicious of any outrageous claims made on the box..."Lose 20 pounds in 5 minutes a day!" or "Melts Fat from Your Abs!" should be clues for you to put that video back on the store shelf. Check to see if the instructor is certified by either ACE or AFAA, the main certifying organizations for group fitness instructors.