I have been reading Dr. Yang Yijin Jing and Xi Sui Jing book! But i also purchase two dvd from Shifu Yan Lei called Qi Gong Vol. 2 Xi Sui Jing and the 2nd one is the Yijin Jing and i also purchase one dvd by Shaolin Monk Shi Guo Lin on Xi Sui Jing and a Yijin Jing dvd by Shi De Qian. But I was wondering why are the training different? and is it safe to practice these dvds? because the master confirm that its safe but dr. yang said that it can be dangerous
http://www.shifuyanlei.co.uk/dvd_shaolin_qigong.html
http://www.martialartsmart.com/dvd-gs009.html
http://www.martialartsmart.com/dvd-bj005.html