One easy peasy question and anyone's allowed to buy this - I reckon prospective purchasers should be made to take a three hour written exam and complete a weekend military assault course, stark naked in the middle of Winter, before even being allowed to enter the site.
Of course, I already have my treasured (videotape) copy !
I borrowed this off a friend a while back, most of it is far too difficult for me but I'm really tempted to buy it because I really love the routines on there.