That video has a few issues. The seven-foot primary hose is not wrapped around your neck twice and the "safe second" as he calls is not there for the sole purpose of a situation where the dive buddy runs out of air. The biggest assumption in the video is that an OOA diver is going to follow a procedure. I have recovered several divers over the years and have spoken to a few survivors that claimed that the diver in distress just swam up and pulled the regulator out of the mouth of their buddy. When folks are truly out of air, they tend to panic and reach for something that they know is providing air. I run a seven-foot hose no matter what type of diving I am doing.
My seven-foot hose is routed down my backplate on my right side, across the front of my waist and under a small knife that I carry on my belt. It is then routed up the left side of my chest and around the back of my neck. My secondary hangs on a necklace and sits right at the top of my chest. In all the junk I have had to swim through doing all sorts of recoveries, I have never had an issue with my long hose catching on anything or causing me an issue. While the long primary is not a requirement for a safe dive, a long primary it is a safer and more versatile way of providing assistance to other divers. Again, this applies to assisting a diver in a true gear failure emergency. If your dive partner simply ran out of air at depth, get a new dive partner.
