Yes, but this is not recommended. Although the DVDs and book illustrations on yoga seem pretty obvious, it is strongly recommended to learn the asanas under the guidance of a teacher. The postures may cause serious damage to the body if performed incorrectly. One must be aware of one's body's signals in attempting the posture. If the posture is difficult, it should not be forced.
Disclaimer: This article contains information on health and wellness and is not a substitute for medical or psychological advice from a qualified doctor and/or specialist.