No, it's not safe. It's a very foolish and dangerous thing to do.
Is choking-out / blood choking safe? I was assured it was, but after seeing it done to my friend, he fell to the floor and eyes kept flickering. It was quite disturbing although he awoke within a matter of seconds.
Cutting off blood flow and oxygen to the brain sound safe to you?
It is leading up to permanent brain damage and/or death.
When you starve parts of your brain . . It dies leaving behind useless grey matter that will no longer support those synapsis from being lit up and used again . . . Sometimes the brain can re-route but rarely does the dead tissue come back. I have seen a lot of MRI's that testify to this.
Anything unnatural to the body
is unhealthy.
No it is not safe. Police were once trained to do this and after a number of deaths and near deaths the practiced was stopped. If someone who trained to "properly" choke someone killed people, what makes you thing someone who saw it online or just heard about it could do it safely?