What you are going to see would shock you - if you have not seen it before. Also I have seen videos of Frogs - look at the first video below which I found later on - floating in air because their bodies had a large content of water, which was ionized when they were put in an intense pulsating magnetic fields!
In Yoga all these powers are described in the Yoga Sutras by Patanjali. To most of the people, this would sound ridiculous.
Some of the advance Yoga proponents have experienced: (1) Involuntary jerking of the body (during Pranayama exercises, specially in the beginning), (2) Involuntary Hopping like a Frog in Meditation (seen on CBS 60 Mins on Maharishi's Transcendental Meditation), (3) Swinging of Limbs with extraordinary force (techniques used by Kung Fu and Karali Monks), and (4) Involuntary Transportation by a few inches doing intense Bhastrika (described by some Sivananda teachers when teaching this and cautioning people to space out between themselves while narrating some class episodes).
This is all possible because of the electrical activity in the body is altered by different Pranayama techniques and combined with mind control and directing of energy by the mind. In my early phases of experimenting with Kundalini Yoga, I could momentarily jerk my body upwards 3 times in one "Kumbha" of Kapalbhati round - and intense heat and sweating was accompanied. But I gave up this pursuit as this is very dangerous and their are recorded aberrations - in unguided practitioners of Kundalini Yoga - at all levels, at physical, mental, and emotional. So it is possible for a "die hard" yogi to "only" pursue this path in their daily routine over a long period of time and achieve these extraordinary powers - specially in the ancient times when the atmospheric oxygen was very high and less toxins in the body were present (heavy metals form air and water pollution and food contamination entering our bodies). I have learnt to 'never say never' and be open and unbiased to any new findings.
I am not sure how this guy does or he has some tricks like hidden aerial ropes (very thin clear polymer strings "loop" strung to another overhead cross clear strings between two high ends) , or clear polycarbonate steps with "inverted 'u' bridges" in the water with passages for "staged swimmers" to swim through the underneath water to show as if nothing is underneath except water (your will see a girl swim below him).