I have both and they are NOT easy! You MUST be sure you have a ball big enough so when you sit on it your knees are not are a 90 degree angle - you need to be sitting high on the ball, so it needs to be bigger. For example - I use a 55 cm ball ordinarily, but for Ball Aerobics I use a 65 cm ball.
A lot of his moves are hard to follow, so if they would be hard to use in a class setting. That being said, I LOVE ball aerobics - there is a huge fun factor, and you really DO get a good workout.
Just Do It!
Interesting...these do look like fun. In the previews the pace looks pretty fast. I think I'd definitely want to get a burst resisitant ball for these.
You can find these workouts right now on Deep Discount DVD for $14.95 each. That is about 10 dollars cheaper than collage a piece. I have ordered from deep discount before and they have good customer service.