true. however, it's all up to you. if you go for it and work up a real sweat, big arms big movements then you do burn these cals. if you go and are learning the routines and don't move much then you will not burn as many cals. also if you have the unfortunate experience of a class where the instructor stops the music after ever song so you can get a drink and it takes like 1 min each time to get back to it then you won't burn as much.
it's all up to you. i did a 45 min class last night and burn 467 cals. my hour classes burn off 601 cals.