I like the Yoga Zone videos, the ones that Alan Finger teaches because he does a very good job with instruction. Yoga Zone's Flexibility and Tone and Flexibility and Stress Relief are two good ones. I also have back issues, in fact, right now I'm nursing a case of sciatica brought on by too much high intensity stepping, so I'm planning on just doing yoga workouts for a week.
BTW, tight hamstrings and tight hip flexors can make back pain worse. You should look for yoga workouts that emphasize opening up and stretching these two areas. Eoin Finn's Power Yoga and Power Yoga for Happiness are great for this. Other good ones are Rodney Yee's Yoga for Athletes and Yoga Zones Yoga for a Strong and Healthy Back. Just remember, when starting out, don't force a stretch. Flexibility takes a long time to achieve.