For kettlebells in particular, when I buy dvds, I do look to see what kind of training and certifications the trainer has. Proper form is SO important with bells.
I really appreciate that Cathe is not just jumping on this band wagon. I kind of feel there is a possibility she would add in some exercises with bells into circuit type workouts, but I don't know if I see her doing a full kettlebell only workout, to me it's just not her style.
Great example of someone who is a good trainer, but totally not qualified to be teaching kettlebells or leading a kb workout is Jillian Michaels, her form is not just ridiculous, it's dangerous.