It's a very challenging program. Don't be afraid to take their advice of hitting the pause button to give yourself a bit longer to recover than they take--it tooks several weeks before I could do the Plyometrics DVD without taking additional breaks.
Don't try to keep up with them if they're going too fast for you. You can do the full set of exercises, then rewind to the start of the next exercise. The people on the tapes have already completed the program--you haven't. It's natural that they're in better shape than you are.
And if something comes up--you get a bad virus, you sprain an ankle, whatever--it's perfectly fine to start the program over again, or repeat a week, or whatever you need.