- Is it ok to do this process alone (if no, why not)?
- Who started it?
- Where is the origin of this practice?
- The best process steps to do it.
- The best book about Bhuta Shuddhi (for a more detailed reading).
- And most importantly how to understand the steps in this process, so one would not do it blindly without knowing why he is doing it the way he is.
He teaches hatha yoga. He is a hatha yoga teacher. Hatha yoga is not Vedanta. It is a physical exercise. Krishna condemns hatha practices in the Uddhava Gita (XXIII. 41-42.) as placing to much emphasis on the material body. Sankara recommends in his Aparoksanubhuti (143.) only for beginners and only in conjunction with raja yoga as a means to help teach the body to sit for long periods of time for meditation, but not as a practice in itself or to be done for years and years.
He also gives in the video a somewhat muddled account of the 5 elements. the annamayakosa, the physical body, is made up of the gross physical elements, not the 5 subtle elements per se as explained by him. The gross physical elements are made up of combinations of the subtle elements, but the physical body is not composed of the 5 subtle elements in the simplistic way he is explaining it. For example, the gross element we call water does not directly equate to the subtle element called water.
The practice of Bhutha Shuddhi as thought by Sadhguru Jaggi Vasudev is perfectly safe and effective.
It can be done alone, meaning you can do it alone by yourself, if that is what you mean. You can do it as a practice by itself in case you are unable to do other forms of yoga like Hatha Yoga or Pranayam due to limitations with your body, etc.
Replying to Swamy Vishwananda, By the way, Sadhguru Jaggi Vasudev is not just a Hatha Yoga teacher, it is just a part of the offered teachings of Isha Foundation.