This meditation has been taught by Yogi Ji in 1969. To my knowledge, no video has been made where he describes the technique in the finest detail. Therefore, it not unusual to notice several variations in the way this meditation is taught and practiced by the different teachers.
There is also an evidence; we all have different shapes, different experience of the practice therefore the techniques have to be individually adapted to who we are at this very moment. A student with a large belly, may not be able to apply the locks with the same strength than another one who can roll on his stomach in bow pose for 3 minutes practicing the breath of fire. Depending on your physical abilities, this meditation will be practiced with more or less strength. What is important is to practice it, one way or the other, explore the various way the different teachers teach it and find the way that works for you.
If you are overweight, a more gentle approach with shorter projection of the sound could be more appropriate as a large belly can affect the lung capacity, the diaphragm lacking room to lower during the inhalation. Plus it may be impossible to practice Uddhiyana bandha with a large belly.
What I show in this video will suit more people looking like in the picture with a good control of the bandhas.
Regarding the bandhas, some will keep the mulband constantly during the all length of the meditation, some will keep it until the 'HEY' and release it after “GURU'. Some will do it a different way.
In this video, I mention to release the root lock at the end of the “Kar”, during the second full inhalation, as I found we can have much more power that way to project the energy into the chest, above the diaphragm during the “Sat”, instead of having to keep the mulband tight all the time.
I have to mention that the way I tight the mulband is not gentle. It's a lock, an airtight one. Therefore it's quite challenging to keep this lock for 7 minutes in a row, even more 11 minutes, 31 minutes or 150 minutes. I'm very much in a awe toward those who can achieve that. If you can, that should be a great experience for you. Personally I teach only what I can achieve and my mulband loose strength if I can't relax it, while it gain strength when I play with the energy by opening and closing it successively.
Practicing is the key to find what works for you. Experiment, don't let your mind prevent you to practice because a technique is taught this way or that way. Initiate yourself because no one will do it for you.