Just wanted to pass along that Bill has started adding the Y-Drill video series to his Blog http://www.billhillmann.net (Click on Blog)
It seems a common question that arises by those that have seen the puppy video, and some of Bill's other material, is how does Bill work on marking?
I think this will provide an insight into the "practice" side of developing marking. It provides 2 reps of contrasting angles for the dog to see and immediately compare the differences.
If you frequently train alone, this is a great drill that only requires You and your dog, a bumper, and five minutes.
Anyhow, just wanted to pass that along...........