I completely agree with bilyeuamber on this one! I think this is a natural horsemanship type way of loading/sending on a trailer and it can work for both a fearful horse and a dominant horse who just doesn't want to load. The idea is to make the inside of the trailer a more comfortable place than the outside. By working them outside the trailer by circling when they refuse to load, they quickly learn that loading=rest.
With previous experiences, I would suggest a long marine grade rope (or lunge line) instead of a lead rope so if the horse refuses, rears, and/or bolts from the trailer they cannot escape by pulling the lead out of your hands (my guy got the lead rope out of my hands a few times and thought he could get out of loading if he reared and bolted...I finally got smart and switched to a longer rope).
I have found that once a horse respects you enough to ask what you want them to do and are willing to try for you, trailer loading can become a wonderful experience with great results!