Can one depend on Yoga cds and yoga dvds and learn all the yoga techniques properly?

My suggestion (and preference) is for a qualified yoga instructor to see my yoga postures in person. Proper technique makes all the difference in the world. After you learn basic postures, yoga videos may help, but in the initial stages of learning, you're best helped by having someone there to observe and make sure you continue with the right postures and monitor your breathing, etc. You can learn proper technique and also avoid possible injury too.

BTW, I just noticed this: what does your tag for yogurt have to do with Yoga?