Any good recomendations for an obedience training DVD/Book to work with prong collar??? Sheila has the basics down alright, just a matter of fine tuning and she starts the Schutz Club soon, but would like to get some more work done with her before she starts. Found a series of training videos online at http://www.leerburg.com/302.htm, anyone here ever tried or heard of these??? Well invested money, or just your average training videos??