I do the cardio sometimes on STS days. Just because I have it there. The video quality is poor, IMO, and I do not think I would tell someone to buy it...But, having said that...a lot of people like it.
There are two BBC programs so I'm not sure which one you are referring too. I think there may be an infomercial out for his latest right now, which I don't think is as tough as his original set from what I've read. I only own the original set. This one is quite tough! I dread the cardio. It is not the best quality but worth having. If you have a treadmill, you will get even more bang for your buck. There are 5 discs that work one body or two body parts a day (haven't done it in a long time and I've loaned it out) and that is followed by your choice of intense cardio and they have an option for treadmill cardio. The cardio is 20 min. or under but the cardio's led by Barry especially make me want to throw up sometimes AND they are the only workouts where at the 10 min. mark I'm questioning if I can last 10 more mintues. I always go through this mental talk to keep going with his cardio. BBC is great for shaking things up but don't think they will be anything like Cathe or other instructors you are used to working out to production wise.