Let me rephrase your question.
Buying a DVD program without the knowledge and feedback of a professional fitness instructor being present vs. not wasting time and money and hiring a real live professional trainer to be with you and guide you as you exercise.
Or a bit less subtly. Giving your money to a pretty face who is most likely genetically gifted, but still promises you their results without knowing a single thing about you except that you are gullible enough to just spend your money on a flashy advertisement.
Support local business and local professionals.