It sounds to me like you are not ready to move on, since you say you're not able to complete all the exercises. I would say ready to move on is when you can finish the whole thing with relative ease and feeling like you could do more.
Maybe you are not able to do everything yet, but can you do more than on day 1? If yes, then that's great, you are making progress! If it's still just as much of a struggle as ever, perhaps your body needs a rest day, or it could be that this particular video is just not a good fit for you at this point.
SW 5/7/12 - 230
6/7/12 - 223.1 (-6.9)
| Pounds lost: 0.9