I disagree....this kid killed a full grown adult in 30-40 seconds with a blood choke....which means that he was pretty good at it. He probably didn't know what to look for in terms of the guy passing out or about to die. Another guy on this thread tried to say that it takes "4 minutes" after someone went unconscious to kill them...which can't be right.
Sorry, but I'm still going to disagree with you here. The fact that he killed the guy does not mean that he knew what he was doing. In fact, it means the opposite..that he had no clue what he was doing.
I personally, don't know how long it takes, but wouldn't want to find out. Many variables comes into play (ie. size, strength, endurance, etc.). I know that I can make someone pass out in about 10-15 seconds, but during sparring, I usually let go or ease up at around the 10 second mark after knowing that my choke was locked in tight...as there's no Ref there supervising. This gives them a chance to tapout, even though sometimes they continue to fight by taking my goodwill as a free pass out of a choke.
It's just not that easy, in the heat of battle, to know if someone is passing out from an RNC.
A good friend of mine, and training partner is a BJJ Black Belt under Roy Harris. He's done a RNC on me, and I was tapping, before he fully applied it. Why? Mechanics. If you're applying it correctly, it shouldn't take long for the person to feel the effects. And as far as not knowing if someone is passing out...you're telling me there's no way to tell? I disagree.