I would love to know this as well .. I just did my first Zumba workout yesterday at home on the wii.
I did the Zumba 1 ... first lesson = 20 minutes. Burned roughly 200 calories. I felt as if I could keep going ... So I put in the 2nd Zumba video .. Did the Medium length workout on Low Intensity since it was my first time ... 44 minutes later, I had without a doubt, had a workout! It said I had burned approx 497 calories ... So between the 2, almost 700 for the hour and 4 minute workout!! Hopefully if I keep it up I'll start to see some kind of results!