Rushfit is great. I tried it out as a way of doing cardio after lifting, but it's way too intense to do on days when you lift. For about a month I just did the video workouts and stopped lifting, and it was working pretty well. I lost weight and my core got much stronger. It all depends on your goals though. If you're trying to build a lot of muscle, it's obvious not ideal, but if you're just trying to get more fit without wasting a lot of time(10 minute warmup,five 5 minute rounds), then it's great. It's a lot safer than those other crappy videos too.
I still do the core workout video a few days a week.