"The main argument here is there are those who think the weight can travell forward without using the feet or the knees and thighs as the propellant."
Yes, if the body is already, which teh majority of the time tt will be...
"To those I would suggest that they glue their feet to the floor."
Okay.
"Bind their ankles knees and thighs."
Fatal mistake - this has no correspondence to dancing.
"Now try to move your body weight forward still keeping the body verticle."
No problem, provided that only your feet are restrained.
Granted, you can only travel so far before you have to move the free foot, but his travel before the free foot moves is extremely important.
"Somewhere in a Foxtrot group there would be a variation where the body momentaraly is in free fall. like a Rumba Walk where we go to the point of imbalance before we catch our weight with the moving foot. For my part I cannot remember being taught anything in the Foxtrot like that."
It happens on essentially every step, but it's most obvious on the lowering steps.
"All that writting above just to say we stand up straight and our legs carry our body and not our body carries our legs."
Actually both are true at various points in the cycle of the step. Any leg movement not a result of the body carrying it is absolutely prohibited in the swing dances. Body movement not carried by the legs occurs quite a bit, but so does body movement carried by the legs.
"Anonymous wrote just prior to this to compare an old tape with a recent one, and seemed to be in favour of the old."
Nope, in favor of the new that still incorporates the old, over the more common new that forgets the fundamentals of the old.
"I'll do one better I was there when the foxtrot was done with very straight legs. I doubt that there will ever be a return to those days."
That is still the correct way to dance it if you are not moving much. Deepness of leg bend is direclty related to distance covered - if you are not planning to cover much distance, it's a serious error to bend your legs much. On the other hand, if you plan to cover modern competitive distance, then you need to bend your legs more than they used to. Pretty simple...