When I went through boot camp, circa 1965, the "rear take down and strangle" was taught. We paired up and supposedly knocked out our partner. But one unwise recruit told the instructor, his partner could not do it. So the instructor put the recruit in the hold, counted the 7 seconds and release. The recruit fell to the ground, eyes wide open. He looked dead. The instructor then stepped hard on the recruits stomach area, forcing air into his lungs, and the recruit came back, coughing and spitting. Hopefully demonstration of this hold has been outlawed, but I fear not, because the seals had been trained.