Which video?
I don't have Mega Step Blast, but that seems to be one many people suggest starting with. I do have the other three videos -- of these, I think Step Heat would also be fine to start with. It has the least complicated choreography and is a little bit shorter (the overall length of the video is about the same, but since that includes abs, the aerobic portion is shorter). Stepfit is definitely the most intense and complicated of the ones you have--it's one to work up to -- while Step Jam is somewhere in between.
Also, when I first started doing Cathe's videos, I would drop the step down a level from what I was used to. Then I gradually raised it a section at a time. (I would do just the first section on a higher step, then drop it for the rest of the video. After a week or two of that, I'd do the first two sections on the higher step, etc.) I think this really helped me make the transition from intermediate videos to Cathe's.
Have fun!
Audrey
