I actually never recommend videos.
Beginning yoga should involve 2 steps:
1. Take a class at a studio with certified yoga instructors.
2. Get some good reading materials and take the time to read them so as to understand the ideas and intentions behind yoga.
Yoga is much more than a bunch of funky poses and stretching. And while you don't necessarily have to ascribe to the spiritual philosophies central to the practice - yes, you can embrace yoga as a purely physical practice - it's important to at least learn and develop a basic understanding of its origins, purposes, etc. I always recommend this book:
It's one of the best I've read and I treat it like my yoga bible when I need to refresh on breathing techniques and asanas. (Although I've practiced yoga for 12+ years. In my first 1-3 years I asked my instructor/yogi most of my questions. My first yogi was the person who told me about this book originally and she was in her 70s, having practiced yoga since the 50s!)
Videos for yoga - esp. anything by Rodney Yee - are ok, but really miss out on the instructor/student hands on experience and do not provide the full scope of resources you can get from an instructor and a good supplemental text like the book above.