On the back position in Jiu-Jitsu, the famed John Danaher has this to say:
No other weapon in the jiu jitsu submission arsenal offers such variation in severity of application as the back/strangle combination. It can go from a mild hold-down/immobilization to a safe means of rendering an uncontrollable opponent safely unconscious; to a truly brutal elbows-to-the-back- of-the- head beatdown position to a lethal strangle in a life or death struggle. No other submission offers this mix of versatility allied with safety and high percentage success rate. As such, the back and the mata leao strangle are the most symbolic representation of jiu jitsu.
The infamous Vagner Rocha had an incredible choke from the back a few months ago, where he trapped an arm with his leg, blocked an arm with his arm and with his free arm put his hand over the opponent’s mouth causing him to suffocate. This sub is not IBJJF legal that’s for sure!
He calls this the Python Choke:
Here is how he does it:
Here he has a more detailed instruction:
Bruno Malfacine Is The Greatest BJJ Competitor Ever To Step On The Mat & For The First Time Ever – The Only 10x Weight Class Black Belt World Champion In History – Wants To Show You How He Wrecks The Big Guys .