I did attend a thing at our hospital that was actually done by Tom Phelan explaining the reasoning and uses of 1-2-3 Magic. This was AFTER I had started using it and had seen the video. My dd is ADHD and it helped ALOT!!! I still find myself using it in a varied way now that she is older.
The whole thing behind it is after you do the "time out" procedure or you hit 3 and go ahead with your discipline (usually a time out) you DO NOT discuss the incident with the child. It allows it to not be "drug" on and on and start an "arguing" phase about the incident.
It really is a good program IF you MAKE it work. Another thing he suggests is, if you get the video, to have your kids sit down and watch it - or parts of it (it's long) so they KNOW what is going to be happening and they understand some of the reasoning. I did this with my dd and she was about 5 - wasn't a problem.
One thing you have to remember is you have to use consistency - you can't do this one time and then not do it the next. So once you start it you need to be committed to it. If you have any more questions, please pm me and I'll see if I can help.