Of course you are right, squarerigger.
I'd say I'm really more frustrated at the moment just by that; I don't have a suitable partner to take the videos that I have to do for the instructions, covering exactly what it looks like from the position of the knot tyer. However, I have done these instructions many times irl, so I know that I must show what it looks like from inside the hand instead of just trying to make someone else mirror what's seen from front.
And I think we won't need the farmer's field or barn for a farmer's knot; we need only as much environmental support, that one can imagine and train. Because just as you say, walking is not learned by watching a speed walker from front. Walking is learned by repeating over and over, sometimes falling, but never giving up.
And tying on a table may indeed be a way to start, but I don't do that with the firefighters, and I don't think it's a lot of help for them to learn the usual seaman's method, as it is of no use for them. They are not tying up ships, they may be dragging out people from dangerous environments or attaching the rope to something they find, whether as a strongpoint or for moving it. In essence; every time this knot has to be tied, it is tied into a closed structure and never laid over a post or bollard.
But of course, it is worth the while to know what the knot pattern is like; it is a help while you rehearse the dance, so you can check that you did it right.
What's common, between the art of walking and the art of tying a knot, is that it has to be rehearsed over and over, until you no longer have to think about it, but just do it.
Postedit: Indeed some knots may be tied on a table, or as in this case, on the floor in an instructive way. It amazes me however, that among several videos on YouTube on how to tie a bowline knot, I didn't find any with this method:
http://www.youtube.com/watch?v=KLtmkV5Z9c4 So indeed, instructions can be done outside of the actual environment; the most important thing is that the instructions are correct and next comes that they are easy to follow. Then of course, you should be able to do it also in the environment where you are supposed to use the knot.