The Firm Fitness Express Thin in 30- How many calories?

Got the Firm Fitness Express Thin in 30 on Monday and I am wondering how to log the exercise. Would I put down 40 minutes of activity as it says one 20 minute workout burns as many calories as a 40 minute one or only 20 minutes? I don't have a body bugg or Fitbit so I don't really know what would be the best way to record this. One side of me is like, "you only did 20 minutes so that is all you can put down" but I really like seeing the calorie burn on the 40 minutes of activity. Maybe right now it doesn't matter as I have almost 70 pounds to lose for my first goal and my calories are always at a deficit right now anyway? Does anyone know what this would count as? I look forward to your advice.

I am quite out of shape and have decided after doing the first DVD that I am going to stretch it out to Thin in 90 as I struggled to get the moves of the video and felt that if I am to get the best results I should actually be doing the exercises as she was doing them and not flailing around like an oaf. LOL So I am going to do each DVD 3 times making their 4 week program a 12 week one.