I tried the 30 day shred. Let me just say that I scoffed when I read that you could lose 20 lbs in 30 days doing this dvd every day- I understand why they said that! It was a rough 20 minutes! Basically, you do a 2 minute warmup, and then three circuits of 3 minutes of strength, 2 minutes of cardio, and one minute of abs, then a 2 minute cooldown. So, the actual exercise takes 20 minutes, but there are a few seconds of time between each exercise, so if you plan to do this, give yourself 25 minutes.
I think you could lose a lb a week doing this dvd 3 times a week and nothing else. I think it would take a LOT of willpower to do it every day for 30 days, because I am already sore and I only did it 4 hours ago. :)